203 



I. Ostracothcrcs cynthiae Nobili. 



1906. Osiracoteres cynthiae Nobili. Ann. Sc. Nat. (9), t. 4, p. 301, textfig. 9. 



1915. Ostracothcres cynthiae Laurie. Journ. Linn. Soc. London, v. 31, p. 465, pi. 45, f. 3. 



Stat. 258. Tual, Kei Islands. Depth 22 m. i 9 ovig., in Styela pneuinonodes. 



As has been observed by Nobili the carapace of the 9 is somewhat quadrangular ; that 

 of the cf, which is described by L.\urie, is much more subcircular. It is nearly straight in 

 transverse direction, and also longitudinally, but the anterior third part is strongly curved 

 downward ; a fine toment is found everywhere on the carapace ; its lateral margins are distinct 

 and convergent backvvard and the posterior margin is .straight. Regions are not discernible. 



In front view of the animal the front is seen to be continued by a triangular septum, 

 directed backward, between the almost transversely-folded antennulae. The eyes are very 

 small, though quite distinct, and concealed beneath the short toment, that covers also the 

 epistome, the epibranchial, subhepatic and subbranchial regions. The antennae are so extremely 

 minute that they scarcely reach beyond the small, circular orbit ; the antennulae are much 

 stouter, the outer flagellum is very short and provided with a tuft of long olfactory hairs, the 

 inner flagellum much longer, slender, cylindrical. The external maxillipeds are covered with 

 the usual, short, feathered hairs, among which generally mud is retained ; it agrees better with 

 L.^crie's figure than with that of Nobili, inasmuch as the propodus is about twice as long 

 as the carpus, not widened distally and rounded at its distal extremity, not obliquely-truncate, 

 but the distal margin is not concave, as stated and figured by L.\urte (for the cf ) ; in my 

 specimen the carpus is not so short and globular as figured by this author. 



Chelae entirely covered with a dense toment, so as to conceal the exact shape of the 

 fingers ; palm inflated, (its basal ventral part flattened in the cf, according to Laurie), about 

 as long as the fingers, which are apparently gaping in the cf (Laurie), but nearly apposed 

 in the 9 ; fingers nearly straight with downy hairs along the free margins, decreasing regularly 

 in height distally, but abruptly curved near the tip, especially in the case of the dactylus; at 

 tJie inner margin of the latter two teeth are found, the larger one being placed quite near the 

 base, corresponding to two similar, but larger teeth on the opposite border of the fixed finger. 



The walking legs are short, slender, about i'^j.^ times the length of the carapace, hairy, 

 especially along the inner border of the propodite ; the last pair is not appreciably weaker 

 (though really shorter) than the preceding pair ; the dactyli of the first three pairs are strongly 

 hooked, tapering to a fine point, those of the last pair, h o wever, are much more 

 straightened, curved only quite near the tip, hairy, flattened and notably 

 longer than in the preceding pairs. This disproportion of the dactyli is much better 

 pronounced in the 9 then in the cT (Laurie). 



The eggs heaped up beneath the very bulky abdomen are numerous and of remarkable 

 large size in such a small species, measuring about 0.55 mm. in diameter. Nobili observed 

 that the eggs in Ostracotheres vary greatly in size according to the species : in O. affinis they 

 are no less than 4 times as large as in O. spoiidyli, but exact measurements are not given. 



"5 



