CLARK: OPHIl'ROIDEA. 443 



the (listalinost largest. Tootli-papillae only 3-5 on each jaw tip. 

 Under arm-phites tetragonal with slightly rounded corners, longer 

 than wide, little or not at all in contact. Side arm-plates moderately 

 large, meeting below; each carries 2 or 3 prominent spines; when 3 

 are present, the uppermost is largest and is often very large, its length 

 equalling 2-3 arm-segments and its thickness proportionately great; 

 near the middle of the arm, segments with two or with three spines 

 alternate with considerat)le regularity; the big uppermost spines 

 occur at intervals of 2-5 segments and alternate on the two sides of 

 the arm. Tentacle-scale single, small and rounded. Color (dried): — 

 disk dull light olive with a very few lighter markings; disk-spines 

 dull yellowish; upper arm-plates dull olive but at intervals of 4-6 

 segments, the upper arm-plate is dull cream-color; upper half of side 

 arm-plates and uppermost spines, usually dull olive but when upper 

 arm-plate is cream-color the adjoining side arm-plate and the upper- 

 most spine it carries is usually the same; lower surface of disk and 

 arms, including smaller arm-spines very pale brown; some arm- 

 spines more or less distinctly annulated with dusky or olive. 



Paumotu Islands: Makemo. 



One specimen. 



Although this specimen is obviously immature, it differs so much 

 from previously known members of the genus, it is necessary to 

 designate it by a new name. The name given is based on one of the 

 striking features, the presence of only two arm-spines on many of the 

 side arm-plates. This character taken in connection with the disk- 

 covering, the upper arm-plates and the coloration will serve to dis- 

 tinguish the species at once from all other members of the genus. 



Ophiodermatidae. 



Ophioderma panamense. 

 Lutken, 1859. Add. ad hist. Oph., pt. 2, p. 91. 



Two specimens from Perico Island, Panama, call for no comment. 



Ophioderma pentacantha,^ sp. nov. 



Plate 3; Plate 4, fig. 1, 2. 



Disk, 27 mm. in diameter; arms 145-150 mm. long. Disk covered 

 with the usual coat of coarse, overlapped scales, completely con- 



' irkvTe = five + aKavOa = a spine, in reference to the five arm-spines. 



