IMPERFECTLY-KNOWN SPECIES OF OSTRACODA. 437 



antennal setae are very short and non-plumose, like those of G. W. Midler's genus 

 Pseudophilomedes, but in most cases they are long and strongly plumed. A peculiarity 

 which I do not understand is the presence in a very few female specimens of well- 

 developed eyes, organs of which in most cases I have been able to find no trace ; another 

 unintelligible point is the red coloration, in some specimens, of the teeth of the second 

 maxilla. Of course it is possible that two distinct species may be mixed up in my 

 description, though I scarcely think that is the case. I am not aware that the shell- 

 gland has been previously noticed, and it is only in two or three specimens that I have 

 found it ; the duct which T have figured is probably connected with the gland, though I 

 have not certainly made out the connection ; the structure is probably an excretory one 

 and homologous with the green gland of higher Crustacea. 



Genus Eupathistoma l , gen. nov. 



Shell membranous, in shape not unlike PMlomedes. Antennules and antennas nearly 

 alike in both sexes, and similar to those of Cypridina, except that the antennules of 

 the male have no suckers ; margins of the mouth provided with three pairs of finger-like 

 sensory processes ; mandibles and maxillae as in Cypridina ; terminal armature of the 

 vermiform foot one-sided, consisting of several unequal, slender lashes, the longest of 

 which are longer than the diameter of the limb ; post-abdomen as usual in Cypridinidse. 



In general character this genus is intermediate between Cypridina and PMlomedes, 

 but the sensory mouth-organs are very remarkable, and seem to have no parallel 

 among other Myodocopa. One pair, at least, of these appendages has an arrange- 

 ment of olfactory (V) filaments exactly like that found in the antennules of the 

 Daphniadse. 



Eupathistoma natans, sp. n. (Plate XLIV. figs. 21-26.) 



Shell seen from the side (fig. 21) elongated, subrhomboidal, greatest height equal to 

 more than half the length ; anterior extremity obliquely truncated and slightly concave, 

 distinctly angulated at its dorsal end, very acutely and prominently angular below, 

 where it merges in a wide, well-rounded antennal sinus ; posterior extremity produced 

 below the middle into a wide, bluntly-rounded beak ; dorsal margin almost flat in the 

 middle, sloping rather steeply to the anterior extremity, and with a steeper curve 

 behind to its junction with the posterior beak, ventral margin rather boldly convex, 

 more fully rounded in front than behind ; seen from above (fig. 22), evenly ovate, 

 twice as long as broad, mucronate behind, narrowly rounded in front. Length 

 2 mm. Male and female nearly alike. The sensory mouth-appendages consist of 

 three pairs of finger-like or conical processes (fig. 24), one pair of which (a) are simple 



1 e\nradi)s, sensitive ; ordjuu, a mouth. 



vol. xiv. — part vin. No. 2. — Decemher, 1898. 3 m 



