298 ART. 2. — H. MATSUMOTO : 



arm spines are also very long, in contrast to those of other 

 species. 



Ophiozona (Lyman, 1865) restr. 



Disk covered witli very numerous small plates, the larger 

 ones being surrounded by a zone of smaller ones. Kadial shields 

 small, separated from one another. A trio of disk plates dis- 

 tinctly present between the outer parts of each pair of radial 

 shields. Two long genital slits in each interradius. Oral and 

 adorai shields small. Four or five oral papilla3 on either side of 

 a jaw ; the outermost one is pointed inwards above tlie next 

 papilla, which is the largest. Teeth arranged in a single vertical 

 row. Dental papilla3 absent. Arms rather long and slender, very 

 gradually tapering outwards, with obtuse end. Dorsal as well as 

 ventral arm plates well developed, almost quadrangular, widely in 

 contact with one another through almost the entire length of 

 the arm. Lateral arm plates of either side not meeting above 

 or below. Four or five short arm spines. Two tentacle scales 

 to each pore. 



This genus, as here restricted, includes Ophiolepis impressa 

 LüTKEN, 1859, and 0. pacifica Lütken, 1859, the former being 

 the genotype. 



Ophiozona is very near to Ophiolepis, being distinguished from 

 it only by the total absence of supplementary dorsal arm plates. 



Ophiosona is wholly a littoral form, like Ophiolepis, and ranges 

 to the West Indies and the Pacific side of Panama. The fauna^- 

 of either side of Panama closely resemble each other, apparently 

 as a result of a former open communication. The distribution of 

 Ophiozona, as well as of Ophioderma, is interesting in this respect. 



