l_j.O SMITHSONIAN .MISCELLANEOUS COLLECTIONS 



232. ASTHENOGNATHUS IN-ffiQUIPES Stimpson 



Plate XIV, Fig. i 



Asfhenognathus inceqiiipcs Stimpson, Proc. Acad. Nat. Sci. Phila., x, 

 p. 107 [53], 1858. 



The remarks under the head of Caniptaiidritiui scxdciitatum will 

 apply with equal justice to this species. 



The specimen is lead colored. Its dimensions are : Length of 

 carapax, 0.29; breadth, 0.375 i"ch. Proportion, i : 1.28. 



It was dredged from a sandy-mud bottom in thirty fathoms, ofif the 

 east coast of Niphon, in latitude 38° X. 



XENOPHTHALMID.^ 

 Genus XENOPHTHALMUS White 



This genus is very imperfectly described by White, like many 

 others instituted by him. We give below a few of its more im- 

 portant characters, by which it will be seen that it is not properly 

 included in the Pinnotheridae, but is the type of a new family. The 

 equality in size between the meros and ischium-joints of the outer 

 maxillipeds is a prominent distinctive feature, since the most im- 

 portant family character of the Pinnotheridse is the rudimentary 

 state of the ischium. Alilne Edwards, in including the genus in that 

 family ("Melanges Carcinologiques," p. 186), was probably guided 

 only by the figure and descriptions of White. 



The carapax is notched at the margin on each side, as if con- 

 stricted. Antennulae minute ; fossettes very shallow, or none. An- 

 tennse robust. Eyes minute, movable, placed longitudinally in deep 

 chinks, and apparently destitute of black pigment. We have failed 

 to observe the "cylindrical tooth" spoken of by White. As in 

 Hyniciiosonia, there is no distinct epistome. In the outer maxilli- 

 peds the ischium equals the meros in size ; the palpus is spirally 

 twisted; dactylus in form resembling that of Pi)uiofhercs. The 

 chelipeds are very small, even in the male. The anterior margin of 

 the sternum projects in the form of a thin laminiform crest, and is 

 separated from the adjacent parts — bases of the maxillipeds and 

 feet, etc. — by a very deep chink or fissure. The verges are sternal. 

 The male abdomen is oblong, not dilated at the base, but of nearly 

 the same breadth throughout ; a slight contraction at the fifth joint ; 

 extremity obtuse, reaching quite to the anterior margin of the 

 sternum. 



