MUSEUM OF COMPARATIVE ZOOLOGY. 173 



of the epizygal forms a sharp angle which projects backwards into the retreat- 

 ing distal face of the hypozygal. 



Examples of this species were dredged by the " Blake " at the following 

 stations : — 



1878-79. No. 157. Off Montserrat. 120 fathoms. 

 No. 281. Off Barbados. 200 fathoms. 



Remarks. — This species is at once distinguished from P. decorus by the short- 

 ness of the internodes of the stem and the absence of any enlargement at the 

 nodes. The calyx is closely similar to that of the variety of P. decorus with 

 small basals, but the arm-bases have a totally different appearance from those 

 of that type, owing to the peculiar nature of the syzygy in the second brachials 

 and in the subsequent syzygial joints. The two apposed face3 are not plane as 

 is usually the case, but the hypozygal has its distal face sharply incised, while 

 the proximal face of the epizygal is in two planes, which make a sharp angle 

 with one another and project backwards into the hypozygal. This peculiarity 

 is best seen in a side view of the arm, unless the joints are separated by boiling 

 with potash or soda. The only other species of Pentacrinus in which it occurs 

 is the ten-armed P. naresianus from the "Western Pacific. In both cases it may 

 be traced in all the syzygies of the avmis, so that small fragments of them are 

 easily recognizable. 



Both the recent species of Rhizocrinus occur in the Caribbean Sea. 

 R. lofotensis was dredged in the Florida Straits by the late Mr. Pourtales, 

 a few months before the publication of M. Sars's well-known description 

 of it ; and R. raiosoni, first found by the " Hassler " off Barbados, was 

 subsequently obtained by the " Blake " in 1877-78 and 1878-79. 



So far as my information goes, the distribution of these two species is 

 as follows : — 



R. lofotensis. 

 Bibb. 1868. Off the Samboes. 237 fathoms. 



Off Sand Key. 248 and 306 fathoms. 

 1869. Off Oojima near Havana. 450 fathoms ; and several times at 

 lesser depths. 

 Blake. 1877-78. No. 29. Lat. 24° 36' N, Long. 84° 5' W. 055 fathoms. 

 No. 43. Lat. 24° 8' N, Long. 82° 51' W. 339 fathoms. 

 No. 44. Lat. 25° 33' N., Long. 84° 35' W. 5:?!) fathoms. 

 No. 56. Off Havana. Lat 22° 9' N, Long. 82^21 I 

 175 fathoms. 



R. rawsoni. 

 Hassler. 1872. Off* Sandy Bay, Barbados. 100 fathoms. 

 Blake. 1877-78. No. 32. Lat. 23° 32' N., Long. 88° 5' W. 95 fathoms. 

 Off Havana. 175 fathoms. 



