TITANOSOMA AND POLYMICRODON IN ENGLAND 163 



more or less evident vestige is to be found, or instead of this 

 rudiment of a telopodite there appears a small, strongly 

 pigmented joint, forming a sort of knot on the coxal knob. 

 In this case there is to be seen at the end of the knot a faint 

 indication of still another joint. 



As regards P. latzeli gallicum, its justification as a sub- 

 species must be tested by means of a longer series of speci- 

 mens. As points of difference from the typical latzeli I am at 

 present able to name only the following : there are no flaps 

 between the distal processes of the syncoxite ; the excavation 

 in the saddle-like process on the sternite of the hinder 

 gonopod-segment is deeper. 



The cheirites of Polymicrodon (X. 7) are very peculiar; 

 they agree with those of Macheiriophoron in the presence of a 

 projecting process hooked backwards at the end, but this is 

 found in a different position in the two forms, in Polymicrodon 

 at the end, in Macheiriophoron at the base. Altogether, in 

 fact, the two cheirites are very differently constructed, that 

 of Macheiriophoron strongly inflated, that of Polymicrodon 

 hollowed out posteriorly, and the cavity (X. 7, fo) overhung 

 by a striated flap (Jo). The distal process is bent back 

 towards the flap and the cavity in the form of a grapnel. 



Let us now glance again at the genus Dyocerasoma. The 

 cheirites possess neither the inflation of Macheiriophoron nor 

 the grapnel and the striated flap of Polymicrodon; on the 

 syncoxite there are in the middle two or three flaps, and on 

 either side there is a serrated plate, which certainly recalls the 

 sickle-plate of those genera, but is not overhung by any 

 process. Dyocerasoma is especially different from Polymi- 

 crodon and Macheiriophoron in respect of the sternite and the 

 joints of the posterior gonopod segment; for the sternite is 

 depressed and bears no processes either externally or in- 

 ternally ; while the joints are developed in the form of large 

 coxites, which come into contact in the middle line at their 

 base, and distally are gradually drawn out into a process. 

 Of a clearly defined telopodite there is nothing to be seen. 



