640 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 

 Family Pal^tsmonid.e. 



PalvEMON Ohionis, sp. nov. 



Carapax smooth, stout, and considerably swollen ; the auteunal and 

 hepatic spines acute and of nearly equal size. Rostrum short, reaching 

 scarcely to the tips of the antenual scales ; its height in the middle about 

 a third of the length, with a very high and arched lamellar crest 

 above, not extending back of the middle of the carapax, and armed 

 with ten to twelve slender teeth, of which the two or three posterior are 

 back of the bases of the ocular peduncles, and more separated from each 

 other than the anterior ones; inferior edge arcuate and armed with two 

 or three teeth ; the terminal third or fourth unarmed and directed 

 slightly upward to the acute tip. Antenna! scale about two-fifths as 

 broad as long ; the edges nearly parallel 5 the tip broad, subtruncate. 



First pair of legs smooth and slender, the carpus, in large specimens, 

 reaching beyond the tips of the antennal scales ; merus and carpus sub- 

 equal in length ; hand very slender, about half as long as the carpus ; 

 fingers not quite half as long as the whole hand, cylindrical, armed 

 with a few fascicles of seta:'. Second pair of legs slender, either equal 

 or somewhat unequal on the two sides; the ischium, merus, and carpus 

 subequal in length ; the carpus, in full-grown specimens, reaching much 

 beyond the tips of the antenual scales, cylindrical, tapering proximally, 

 and armed with scattering spinules, or short hairs ; hand considerably 

 longer than the carpus, slender; the basal portion of the propodus 

 slightly swollen, nearly cylindrical, and armed with minute spinules ; 

 the fingers much shorter than the basal portion of the propodus, slender, 

 not gaping, nearly straight, and armed with a few fascicles of short 

 setiform hairs. Succeeding legs increasing slightly in length posterior- 

 ly ; all of them with short, strongly-curved dactyli, and reaching slightly 

 beyond the tips of the antennal scales. 



Fourth and fifth segments of the abdomen produced at the posterior 

 lateral angle, which is rounded in the fourth segment and acutely angu- 

 lar in the fifth. Sixth segment only a little longer than the fifth. Tel- 

 son narrow, considerably shorter than the inner lamellie of the append- 

 ages of the sixth segment, tapering regularly to the acutely triangular 

 tip, which is armed each side with two slender spines and numerous 

 long plumose set*; the dorsal surface armed with two pairs of -short 

 spines. 



Two specimens give the following measurements : 



Male. Female. 



mm. mm 



Length from tip of rostrum to extremity of telson 51 . 80. 



Length of carapax from orbit to middle of posterior margin 12. 22. 



Breadth of carapax 7. 8 14. 



Length of rostruni from its tip to base of ocuUir peduncles 8. 2 13. 5 



Length of basal scale of antenna 8. 4 32. 



Length of first pair of legs 16.0 8. 3 



Length of merus in first pair of legs 4. 2 10. 



