22 Dr. A. C. Stokes on some 



lateral two extending to the ventral surface, their outer borders 

 apparently thickened into a small chitinous hook, the inner 

 surfaces of these membranes coming into contact when the 

 body is retracted, then frequently forming a nipple-like pro- 

 jection ; brain large ; oesophagus lined by long, conspicuous, 

 flagella-like cilia, which are pendent into the stomach. 

 Length, including toe, y^^ inch. 



Monostyla robusta, sp. n. (PI. VII. figs. 9 and 10.) 



Lorica subcircular in outline, but little longer than broad ; 

 ventral surface flattened, dorsal arched, steeply sloping ante- 

 riorly when the animal is contracted, the frontal region of the 

 lorica being flexible ; frontal borders concave, undulate, the 

 ventral with a broad central emargination ; each lateral 

 frontal angle terminated by a short incurved acumination; 

 toe rod-like, straight, terminating in two short acuminate 

 claws, distinctly parted, especially at their extremities, and 

 projecting from between two small setiform spines ; entire 

 lorica coarsely punctate, lateral antenna} small, projecting on 

 each side within the lateral sulcus, near the posterior extre- 

 mity and from the upper surface of the lower or ventral 

 region of the groove ; dorsal antenna a single setigerous 

 circumvallation ; brain conspicuous, large ; eye single, large, 

 circular, red, granular, and superficially placed near tiie middle 

 of the nerve-ganglion ; the stomach bears internally, near the 

 entrance of the oesophagus, a ligulate undulating membrane 

 (or tube ?), coarsely striate longitudinally, and about yuDU ii^ich 

 long. 



Length of lorica, including toes and claws, yI'S i^i^h ; 

 length of lorica alone j^ inch ; width -gyg. Toes and claws 

 together about one half as long as the lorica. 



The claws are distinctly, even conspicuously, two, being 

 visibly parted throughout their entire length, and actually 

 separated at their tips; they are immovable, or appear to 

 be so. 



The general form, the frontal acuminations, the parted 

 claws between the setiform spines make the species one that 

 is easily recognizable, and not likely to be mistaken for any 

 other thus far observed. 



No varieties of the species have yet been found, although 

 one or more may probably exist. I have, however, observed 

 a specimen with the toe and claws as shown in fig. 10, where 

 there was but one setiform spine, stouter and more conspicuous 

 than usual, and where the toe was undulate and peculiarly 

 malformed. 



