THE BLASTOIDEA 93 



PENTEPHYLLIDAE. Theca subpentagonal, stemless ; RR asymmetrical. 

 Ambulacra linear, stretching down to base. One shorter than the rest. 

 Genus Pentephyllum. FAMILY 4. ZYGOCRINIDAE. Theca depressed, stem- 

 less, asymmetrical, quadrilobate. Four ambulacra between the lobes, 

 accompanied by a single hydrospire on either side. Fifth ambulacrum 

 shortened and widened. A large. Genus Zygocrinus. 



A Bibliography of the Eublastoidea was given by R. Etheridge, jun., 

 and P. H. Carpenter, " Catalogue of the Blastoidea in the . . . British 

 Museum," London, 1886. A complete index of names with references 

 to literature is furnished by F. A. Bather, " The Genera and Species of 

 Blastoidea, with a List of the Specimens in the British Museum," London, 

 1899. For other references see Nos. 16, 17, 25, 27, 30, 34, 38, 45, 50, 

 60, 64, 69, 71, 73, 75, 76, 77, 78, 82, 84, 85, 94, 95, 96, in the list at 

 the end of Pelmatozoa (p. 211). 



