REPORT ON THE AMPHIPODA. 1495 



abruptly contracted for a little space, beyond which the gentle convergence is 

 continued. 



Length, in the rolled position, less than a fifth of an inch, and scarcely longer than a 

 fifth if unrolled. 



Locality. — Station 106, August 25, 1873; between St. Vincent and St. Paul's Rocks; 

 lat. 1° 47' N., long. 24° 26' W.j surface to 40 fathoms; surface temperature, 78°-8. 

 Three specimens, that described a male. 



Remarks. — The specific name is given out of respect to the founder of the genus. 

 Dana's Thyropus diaphanus was taken in the "Atlantic, latitude 4° 25' south, longitude 

 21° 30' west ; " its " length, when extended, one-fourth of an inch ; when folded up, one- 

 eighth of an inch." It agrees in many respects with the species just described, but, if 

 Dana's figures and descriptions may be trusted, it has the apex of the first joint of the 

 flagellum in the upper antennae produced over the base of the second joint, the second 

 joint of the flagellum of the lower antennae much less than half the first, the telson 

 subacute, and the rami of the third uropods subequal. The last two characters cannot 

 possibly be reconciled with the Challenger species, or with Thyropus sphseroma (Claus). 



Thyropus sphseroma (Claus). 



1879. Tanyscelus sphseroma, Claus, Die Gattungert und Arten der Platysceliden, p. 17. 



1887. Thijroims sphseroma, Bovallius, Systematical List of the Aniph. Hyper., Bihang. till K. 



Svensk. Vetensk.-Akad. Handl, Bd. 11, No. 16, p. 43. 

 1887. Tanyscelus sphseroma, Claus, Die Platysceliden, p. 45, Taf. viii. figs. 1-11. 



The Challenger specimen corresponds closely with Claus' figures and description. 

 There is the distinguishing line of little spots of colour partly on the side-plates and 

 partly on the adjacent margins of the segments ; it is distinguished by these from 

 Thyropus danse, above described, as well as by the fifth peraeopods, which have a slender 

 fourth joint much longer than the third, and a short fifth joint. The distal end of the 

 first joint of the fourth perseopods also appears to be less narrow than in the preceding 

 species. 



Length, at full stretch, scarcely a fifth of an inch. 



Locality.— April 29, 1876, North Atlantic; lat. 18° 8' K, long. 30° 5' W.; surface, 

 night; surface temperature, 73°"7. One specimen, male. 



Remark. — -The back of the perseon in our specimen, though tumid and rounded, 

 shows a tendency to be irregularly arched. 



