¹ Malloch (1914), in his paper, gives ample reasons against the adoption of the generic name Melusina Meigen in place of Simulium Latreille, and establishes the validity of the latter.

² Prom the accounts of Pomeroy (1920) of the early stages of some of the African Simuliidae, it seems probable that a further knowledge of the pupal stages of the other little-known species may reveal forms intermediate between Wilhelmia Enderlein and Eusimulium Roubaud, which are separated from each other only by the difference in the structure of the pupal respiratory filaments.

¹ The larvae I have studied proceed to build their cocoons as follows: (a) The larva at first spins a loose network of threads on the substratum between various points laid down at random on the flat surface just behind it. (b) Continuing, it spins threads passing dorsally over its body, whereby the cocoon becomes clearly defined, as a loose basket, (c) It now frees itself and becomes fixed at the cocoon-opening and thickens the network from the inner side.

¹ Oviposition under water has been observed by Britten and Edwards in S. equinum as follows: The female enters the water where the current is not very strong, walks along a twig to a depth of several inches, with her wings wrapped round her abdomen, thus enclosing a bubble of air. She then lays her eggs on a twig or leaf. Having oviposited, she releases her hold and rises to the surface of the water.

¹ This may be another remnant of the tentorium, or of a branch thereof.

¹ The antennae of the larvae of Simuliidae always have a very small terminal portion, which Meinert (1886) and Friederichs regard as merely a sensory seta; Planchon, Riley, Edwards and others, however, regard it as a segment. Consequently some confusion has arisen as to the number of antennal segments in the various species. In the present paper the terminal portion is regarded as a segment.

¹ Frontal nerves from the two sides unite to form the median Frontal ganglion of the visceral nervous system.

² These mouth-brushes resemble the cephalic fans of Simulium larvae, both in position and to some extent in structure and according to Howard (1912) and Thompson (1905) are only lateral parts of the labrum.

¹ Some authors have wrongly described the palps as made up of three segments (Patton and Cragg, 1913), others as of two (Planchon and Verdat). The thinly chitinised distal portion, which at times appears slightly constricted, has probably been mistaken for a separate segment.

² I have followed the nomenclature of de Meijere (1916) for the various parts of the labium. Unlike the other larvae described by him, however, in Simulium larvae it is the Submentum that ia hard and toothed and not the Mentum.

¹ Wrongly called the “labium” by many writers; some call it the “mentum.”

² Grünberg (1910), Planchon and others have described the abdomen as composed of nine segments.

¹ The colour of these granules varies in the larvae of different species.

¹ Strickland (1913), in his figures of the oesophageal valve, wrongly shows the muscular layer extending only about half-way into the cardiac chamber. In fact, in some sections a double layer of muscle-cells is seen in the apical region of the valve, which leads us to the conclusion that even the muscular layer is reflected to a very small extent. But the cells in this region are much enlarged and vacuolated, with few or no muscle-fibres.

² According to Van Gehuchten, this cavity is filled with a finely granulated mass like coagulated blood-plasma but with no blood-corpuscles and the whole is traversed by an irregular network of fine fibrils which disappear on the epithelial membrane externally.

¹ The nomenclature is that used by Berlese (1909).

¹ It is similar to that described by Taylor (1902) for Simulium latipes.

¹ In the larvae of some species of Simuliidae (such as S. hirtipes Fries another, though much finer, initial thread arises from the main trunk in the eighth abdominal segment). Very probably it is present in all the species but is too small to be distinguishable.

² The eighth abdominal spiracle is situated on the dorsal surface of the larva but is much smaller than the preceding ones. It is clearly visible, even under a low magnification in the larvae of S. hirtipes Fries and S. ferrugineum Walb., but in those of other species, it is extremely minute.

³ Meinert and Grünberg regard this spiracle as belonging to the prothorax, while from its position just behind the tergo-sternal muscle between pro- and meso-thorax, Taylor (1902) concludes that it is mesothoracic. But as the main tracheal trunk passes external to this vertical muscle, no importance can, however, be attached to the relationship of the spiracle to this muscle in the present case. Moreover, by comparison with those other apneustic larvae of eucephalous Diptera in which the tracheal system has been worked out (Dasyhelea, according to Keilin, 1921) we find that the most anterior spiracle is pro- and the second meta-thoracic. According to Keilin (1924) the primitive position of Insect spiracles is intersegmental. In Diptera the first pair of spiracles has moved forwards and become prothoracic while all the others have moved back wards, the mesothoracic segment being left without spiracles.

¹ The number of tracheoles in the gills of the larvae of Simuliuin nötteri and other British species is not very large, but in the larvae of S. damnosum and even of S. reptans, found in the tropics, the gills are supplied, according to Roubaud (1906 and 1907), with large tracheae which branch profusely in the walls of the gills.

¹ By feeding larvae of Anopheles plumbeus on carmine granules, I find that this mass is not nephrocytic in function for it does not take up the carmine though the true nephrocytes become fully charged therewith.

² The distribution of nephrocytes was studied by feeding the larva on carmine granules.

¹ For methods see Kowalevsky (1889) and Nuttall and Keilin (1921).

² Miall and Hammond (in Chironomus), Bruntz (1904) (except in Culex) and Imms (in Anopheles) do not mention anything about the Peri-oesophageal nephrocytes.

¹ The presence in younger larvae of relatively longer setae than in full-grown specimens has already been observed in Bibio (Morris, 1921), Forcipomyia (Saunders), Cyclorrhapha (Keilin, 1911, 1915) and appears to be of very common occurrence.

¹ The growth of the antenna in Simulium larvae is rather unusual among Insects, as the increase in the number of segments takes place by addition in the first two larval stages and by intercalation after the second-stage larva.

From the presence of the pair of stumpy projections at the base of the antenna (C, Text-fig. 5), it is obvious that this two-segmented antenna represents the two terminal segments (Pl. IX, fig. 15) of the antenna of a full-grown larva. In the second-stage larva (to be dealt with later) a third segment is added to the antenna from below, while in the third stage a fourth segment has been intercalated between the basal and the second segment of the antenna of the second stage larva.

¹ Respiratory filaments of pupae of Simulium are homologous to the “ Prothorakalhorns” (de Meijere, 1902) of pupae of various other Diptera and have been described as tracheal gills by many writers. On account of the complete absence of tracheae in these filaments of Simulium, Volger (1887) called them Röhren Kiemen (tube-gills) and Taylor (1902), who has described the tracheal system of Simulium in detail, has given them the name of Cuticular Gills.

² At my request Mr F. W. Edwards dissected out the genitalia of this specimen and found them to be like those of a typical S. nölleri.