82 PROCEEDINGS OF THE ACADEMY OF [Feb., 



OPHIOZONELLA gen. nov. 



Disk covered with stout plates, mingled with smaller ones. Radial 

 shields very large; those of both sides of a radius separated from 

 each other by a single row of plates, or more or less in contact with 

 each other. No distinct trio of plates just outside and between each 

 pair of radial shields. Oral and adoral shields rather large. Teeth 

 and oral papillae present; the latter are thick and close-set. Genital 

 slits short, not reaching disk margin. Arms not very long, stout 

 at base, rather rapidly tapering distally to a slender and acute tip. 

 Dorsal and ventral arm plates rhomboidal, successive plates separated 

 from each other, at least, distal to arm base. Arm spines two to 

 four, short. One or two tentacle scales to each pore. 



This new genus includes the following species with two tentacle 

 scales: Ophiozona nivea, tessellata, marmorea and clypeata of Lyman, 

 0. bispinosa and molesta of Koehler, and 0. elevata and platydisca 

 of H. L. Clark; and the following with only one tentacle scale: 

 0. insularia stellata, antillarum and depressa of Lyman, 0. alba and 

 contigua of Liitken and Mortensen, 0. casta and projeda of Koehler, 

 0. tjalfiana Mortensen, and 0. polyplax and longispina of H. L. 

 Clark. The genotype is Ophiozona longispina H. L. Clark. 



Ophiozonella includes deep-water forms and is allied to such genera 

 as Ophiocrates and Ophiofuidas, while genuine Ophiozona includes 

 littoral forms and is very close to Ophiolepis and Ophiothyreus. 



OPHIOZONA Lyman, 1865 (restr.). 



Disk covered with very numerous small plates and scales, the 

 larger surrounded by belts of smaller. Radial shields small, widely 

 separated from each other by several plates and numerous scales. 

 A noticeable trio of plates is distinguishable just outside and between 

 each pair of radial shields. Oral and adoral shields small. Teeth 

 and oral papillge present, latter very thick and close-set. Genital 

 slits rather long. Arms long, rather slender, very gradually tapering 

 distally, with blunt tips. Dorsal, as well as ventral, arm plates 

 well developed, quadrangular, successive plates widely in contact 

 with each other throughout the entire length of the arm. Four or 

 five short, peg-like arm spines. Two tentacle scales to each pore, 

 more or less oval in common outline. 



This genus, as here restricted, includes only Ophiolepis impressa 

 and pacifica of Liitken (the two species on which Ophiozona was 

 based by Lyman). The genotype is 0. impressa. 



The Ophiolepidinse comprises two groups, one of which includes 



