316 ART. 2. — H. MATSUMOTO : 



Ophiurochseta Matsümoto, 1915. 



Disk, as well aa radial shields, closely covered with fine 

 grannies and bearing scattered spines. Oral angles granulated, 

 oral shields naked. Oral papillae numerous, close-set, the outermost 

 papilla being pointed inwards above the next papilla, which is the 

 largest. Arms not very long, rather stout, widest at the base. 

 Dorsal, as well as ventral, arm plates well developed, fnlly in 

 contact with one another. Six or more arm spines, long, flared, 

 longer than the corresponding arm joint. Two tentacle scales to 

 each pore, the abradial one overlapping the base of the lowest 

 arm spine. 



This genus includes Ophiochceta mixta Lyman, 1878 (referred 

 to OphioUmna by Verkill, 1899), and Ophiolimna littoralis Kœhler, 

 1912, the first being the genotype. 



This genus apparently resembles Ophiochceta, bat differs from 

 it in the long and fiared arm spines. Ophiurochœta differs from 

 Ophiolimna Veerill, 1899, in the more numerous oral papillae, of 

 which the outermost one is not very large and operculiform, but 

 pointed inwards above the next papilla, which is the largest ; in 

 the well developed dorsal and ventral arm plates, and in the pre- 

 sence of two tentacle scales, of which the abradial one overlaps 

 the base of the lowest arm spine. Verriijl- thinks that the internal 

 structures of 0. mixta are much like those of Ophiacantha ; but 

 my own observations lead to a quite different conclusion. 



I have observed the internal structures of Ophiuroconis mono- 

 lepis, Ophiurodon grandisquama, Ophiurochœta mixta, Ophiarachna 

 incrassata, Ophiochiton fastigatus, Ophioplax lamellosa, &g., and 

 satisfied myself that they all belong to the same typo. In these 

 forms, the peristomial plates are always triple, one of the secondary 



