dorsal surface of the tail ; these discs have raised edges, and within each are seen 

 three oval slits, which form the terminal openings of the respiratory tract. 



The alimentary tract cannot be demonstrated. 



The larva moves by striking the booklets into the subjacent surface and 

 dragging the body after. When feeding, the hinder end of the body is shortened 

 and fixed by means of the sharp pointed scales already described ; the head 

 and mouth are alternately raised and extended with the booklets protruding, 

 and then depressed with retraction of the booklets, and by a rapid scratching move- 

 ment, the food is dragged into the mouth. 



This description answers fairly well with that of the larvse of MuscidcB given in 

 the Cyclopaedia of Anatomy and Physiology, only Newport lays stress on his 

 observation that the bodies of Muscidce (e. ^., " Vomitoria") are divided into at 

 least 14 if not 15 segments, whereas in the larvae from the toad I can only count 12 

 segments ;* also he describes and draws the disc-shaped respiratory orifices, but he 

 places them in the 4th segment, whilst in my specimens they are on the 12th or 

 last segment. Neither does he describe the gauntlet-shaped anterior orifices of the 

 respiratory tract, which, in the larvae from the toad, are at the junction of the 2nd 

 and 3rd segments. 



Professor Brauer, o£ Yienna, kindly examined some of these 

 larvae for me, and reports that they belong certainly to the genus 

 Callipliora, the species he cannot determine, but suggests that it may 

 be erythrocephala or vomitoria. 



The larva is not truly parasitic, for it speedily destroys the life of 

 its host ; yet it is difficult to regard its presence in the nostrils of 

 toads as wholly accidental, for whilst the disease is extremely common 

 amongst toads in certain years, it is always the nostrils and soft parts 

 of the interior of the mouths which are attacked, and no other parts. 



The fly cannot lay its eggs directly in the nostrils, for there is not 

 room for more than one egg in each nostril at a time ; moreover, the 

 toad would most certainly object to the process. Elies form a large 

 proportion of the food of the toad, and possibly the eggs may be laid 

 in the mouth, whilst a pregnant fly is being swallowed ; the eggs could 

 not be swallowed, would become hatched in situ, and the larvae could 

 promptly devour all within their reach. On the back of my toad 

 were several rows of these eggs, which I unfortunately lost, so a second 

 explanation is, that the eggs are laid indiscriminately on the toad's 

 back ; and the larvae when hatched make for the nostrils as the easiest 

 point of attack. This is supported by their action when placed on 

 raw meat. They at once sought and buried themselves in the nearest 

 crevice or hole, such as a small blood vessel, in which they remained 

 to feed. 



It is probable that the number of toads is largely kept under by 

 these means. 



* This discrepancy is morphological, not real.— R, McL. 



