44 



OPHIOGLYPHA SARSIL 



mouth-shield, and one on the other side ; the rest of the pores have but 

 one scale. Upper side of the disk almost completely covered by pri- 

 mar}' plates and radial shields, which are rounded and much swollen ; 

 of the prhnary plates, there is a rosette of six in the centre, and three 

 in each interbrachial space. A larger specimen had a disk of 7""', and 

 arms 24"'° ; and another had the disk lO.S"""", arms 42°""-. The mouth- 

 shields vary somewhat in proportionate length ; those of the young 

 have a deeper depression where they touch the inner end of the genital 

 slit. The adult have the disk-scales flatter, and the jirimary plates and 

 radial shields more conspicuous, by reason of the many small scales 

 between them. Dr. Liitken mentions a variety (0. corlacea Ltk.) which 

 has only one tentacle-scale, and the disk-scales very small ; and another 

 (perhaps a variety) which has no papillae on the incision of the disk, 

 arm-spines only half as long as in 0. Sarsii, and a hairy or felted cover- 

 ing over the surface {0. arctica Ltk.). The color of the living animal 

 is a mixture of green, yellow, and gray, with sometimes light bands on 

 the arm (Barrett). 



0. Sarsii has been found in Massachusetts Bay, and at the Grand 

 Manan (Stimpson) ; along the whole coast of Greenland (Holboll, Bar- 

 rett, &:c.) ; at Spitzbergen, and on the coast of Norway (Sars). It is 

 distinguished from O. robusfa by the different scaling of the disk ; from 

 0. texhirata, by wanting pores on the under side of the inner arm-joints ; 

 from 0. earned and O. albicla by longer arm-spines ; and from 0. Liit- 

 kenii, by the double row of notch papillae, and by their greater sharp- 

 ness. 



LIST OF SPECIMENS. 



