236 VERRILL 



mally, from the lower row by interpolated plates and is, therefore, 

 more regular and distinct. Its broad disk and very short rays are 

 shared by H. arctica; but in the latter the disk is flat and the oral 

 region is not sunken, while the spinulation is very minute, and the 

 spinules far more numerous and differently arranged on all the 

 plates, but particularly on the adambulacrals. 



Dutch Harbor, Unalaska (Harriman Expedition, Dr. W. R. 

 Coe). 



The name tumida was originally a manuscript name used on labels 

 by Dr. Richard Rathbun, who had recognized this as a distinct form 

 several years ago. 



This is a very peculiar form of Henrida, having a large, swollen 

 disk and very short rays, but in most other respects agreeing so 

 closely with H. borealis that it seems possible that it is only a sexual 

 form or a variation of the latter. 



The peculiar excavate condition of the actinal surface of the disk 

 and oral area seems to be specially adapted to the carrying of the 

 eggs and young. Whether all the specimens were actually females 

 could not be determined from dry specimens. It might be thought 

 that this is the normal female, while H. borealis is the male of the 

 same species, were it not that Dr. Fisher has figured the female of 

 H. borealis, while actually carrying eggs, and it does not agree with 

 H. tumida, but has about the proportions of borealis, and arches its 

 disk as is usual in other species of the genus. There is no evidence 

 given that the arching is persistent, nor that the adoral plates and 

 spines are modified for that purpose. 



HENRICIA TUMIDA BOREALIS Verrill, subsp., nov. 



Plate xn, figures 3, 4; plate LXXXVI, figures 6-60 (details) ; plate LXXXVIII, 

 figures 5-5b (details). 



Henrida eschrichtii (pars} FISHER, op. cit., 191 ib, p. 276, pi. LXVII; pi. Lxvin, 

 fig. I (non Mtiller and Troschel). 



Rays five, short or moderately long, stout, swollen at base, taper- 

 ing rapidly to slender tips. Disk rather large and thick. Radii of a 

 dry specimen, 12 mm. and 42 mm. ; ratio, about i : 3.5. Breadth of 

 rays at base, 15 mm. Another specimen has the radii u mm. and 

 42 mm. ; ratio, about i : 3.8. A short-rayed specimen has the radii 

 10 mm. and 24 mm. ; ratio, i : 2.4. 



The dorsal surface, in dry specimens, has a distinctly areolate 

 appearance, the angular meshes of the network of ossicles being 

 larger and deeper than usual in the related species, and the narrow 



