DESCRIPTIONS OF GENERA AND SPECIES. 289 



tlie excavated posterior margin, flattish notogaster, and 

 thin posterior legs more resemble the female. It is 

 greyish white with light pink legs ; the hairs on the 

 notogaster are very similar to those of the adult, but 

 are riot so long. The marginal parts of the posterior 

 portion of the abdomen have a tendency to be lobose. 



Hypopus (PL XVIII, figs. 5, 6).- 



Length (English specimens) about . . . '25 mm. 



Breadth (English specimens) about . . . '17 



Haller gives his specimens about twice the size. 



This hypopus is homopial, i. e. it adheres to its 

 temporary host not by suckers, but by holding one or 

 more of the hairs of the host between special plates on 

 the ventral surface of the parasite. It was the type 

 upon which Koch's genus Homopus was founded. 



Colour. Light yellow with an orange shade, espe- 

 cially at the sides. Legs and homopial (hair-holding) 

 plates Indian red. 



Texture. Really polished, but the effect of polish 

 is almost entirely destroyed during life by the 

 longitudinal sulcations mentioned below. 



Form, etc. Cephalothorax and abdomen divided 

 by a clear line ; the former about half the length of 

 the latter. Cephalothorax conical, with curved edges; 

 the sides convex, the base concave ; it is fully twice as 

 broad as long, is pointed anteriorly, the point being 

 slightly drawn out); the rostrum is strengthened by a 

 chitinous ridge on its inner surface (PL XVIII, fig. 9), 

 which ridge divides and widens out posteriorly and 

 surrounds the mouth. The anterior part of the 

 Cephalothorax is semi-transparent. Abdomen widest 

 where it adjoins the Cephalothorax, gradually narrow- 

 ing as it approaches the posterior end ; sides convex, 

 posterior margin concave. Notogaster moderately 

 arched ; it is without hairs or any true markings, but 

 during life is usually broken up by a series of irregular 

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