REPORT ON THE CRUSTACEA MACRURA. 123 



The rhipidura is symmetrical ; both outer plates are fringed with ciliated hairs. 



The telson terminates in a sharp point furnished with numerous ciliated hairs on each 

 side, and with many long and slender spines on the dorsal surface. 



Length, 13 mm. (0'5 in.), measured from the frontal margin to the extremity of the telson. 



Habitat.— Station VII. v., off the Canary Islands, February 11, 1S73; lat. 27° 58' 

 N., long. 17° 39' "W. ; depth, 1G20 fathoms; bottom, volcanic mud. 



This unique specimen in general appearance is very unlike any other genus in the family. 



The dorsal surface of the carapace, instead of being compressed, is elevated and has 

 a globular appearance, while the lateral walls are bent under the ventral surface and lie 

 flat in the same plane, apparently, with that of the sternum. It is dorsally covered with 

 spines, or long, slender, sharp teeth, of which two stand longitudinally in the central line 

 on the frontal region, and two on each side, one on each side of the gastric region and 

 two on each side of the cardiac region, two on the upper and anterior portion of the 

 branchial region, and several, which increase in length posteriorly, on the lateral angle 

 formed by the sudden inflection of the carapace. 



The pleon is very narrow and generally lies folded against the ventral surface of the 

 pereion ; it is dorsally armed with long and slender spines, one on each side of the median 

 line and one on the lateral wall of the four posterior somites, just above the margin, 

 which also is armed with a long posteriorly-directed tooth and two smaller ones, except 

 in the case of the sixth somite, in which the margin is produced to a single, long and 

 slender tooth : the telson is likewise armed with long and slender spinedike teeth, of 

 which there is one in the median line near the base, and one on each side still nearer ; 

 these three are the largest, the others are smaller and ranged in rows on each side of the 

 median line from the base to the extremity, which terminates in a small tooth on the 

 dorsal surface, and is flanked with several ciliated hairs on each side. 



The ophthalmopoda are absent, and no trace of organs of vision can be determined ; 

 there is a slight depression on each side near the central line of the frontal margin ; 

 and more laterally, beyond the outer antennas, corresponding with the position of the 

 eyes in Will&mcesia, is a dark spot on each side that is suggestive of being an organ of 

 vision, but the want of specimens for a close examination precludes me from being able 

 to confirm the supposition. 



The first pair of antennas (b) has the first joint short and stout, armed on the inner side 

 with a strong and sharp-pointed tooth that is broad at the base, and on the outer with 

 a fine, anteriorly-directed, spine-like tooth ; the second joint is very short but narrower 

 than the first, and the third is yet shorter and narrower, and supports two unequal slender 

 flagella that are not very long and only sparingly multiarticulate. 



The second pair of antennas (c) has the basal joint supporting a cylindrical rod that is 

 longer than the peduncle of the antennas ; it is obliquely truncate at the extremity, 



