CHARACTERISTIC DEEP-SEA TYPES. CRINOIDS. 



125 



an examination of several hundred individuals, that present any 

 departure from the ordinary pinnule arrangement. 



The two Comatuhe which from their ahundance seem especially 

 characteristic of the neighhorhood of the Caribbean Islands, 

 ransfino; from Santa Cruz to Grenada, are an Antedon and an 

 Actinometra, both of which had been obtained previously to 

 the " Blake " expedition. In the year 1870, Duchassaing 

 brought from Guadeloupe to the Paris Museum a fine spfecimen 

 of Antedon, with thirty very spiny arms. Carpenter readily 

 recognized it in the " Blake " collection, and has named it Ante- 

 don sinnlftra. (Fig. 417.) The common Actinometra of the 

 Caribbean Sea is 

 a singularly protean 

 species, which was 

 obtained at thirty 

 stations by the 

 "Blake." The 

 " Hassler " dredged 

 it off Barbados, and 

 it was found by the 

 " Investio'ator " off 

 St. Lucia, and also 

 attached to the Mar- 

 tinique and Domin- 

 ica cable. It ranges from 73 to 278, and possibly to 380 

 fathoms. Not only is it everywhere very abundant, but it pre- 

 sents a most remarkable series of minor variations on one fairly 

 distinct type, which, under the name of Actinometra puhhella 

 (Fig. 418), includes no less than six forms apparently distinct 

 at first sight. Most of the specimens have twenty arms, occa- 

 sionally a smaller number ; some, however, have as few as twelve 

 to fifteen. Actinometra pulchella is also interesting as fur- 

 nishing an instance of variation from the ordinary type of five 

 rays. One specimen, like that dredged by the " Challenger," has 

 six rays. It is curious that this variation, which is common in 

 Rhizocrinus, should be so rare among the Comatulse. 



The results of Carpenter's examination of the " Challenger " 

 and " Blake " collections, and of the numerous Comatul* to 



Fig. 417. — Antedon spinifera. ^. 



