74 BULLETIN 84, UNITED STATES NATIONAL MUSEUM. 



or, in case they are larger, as an Ophiomitrellaf And wliich size will be taken as a 

 standard for marking the limit ? I mention this case because it seems to me to be 

 one of the most deUcate, and because the difficulty caused by it often arises with 

 the Opliiacantiiidse ; sliould the characters given by Verrill to the genus OpMomitrella 

 be very rigorously appUed, most of tlie OphiacantJisR would finally pass over to that 

 genus. 



Therefore, I repeat that some of the genera proposed by Verrill are absolutely 

 justified and very easy of application, and consequently are worthy of being 

 presci-ved; but I must own that in most cases the generic determination of the 

 Ophiacanthidse is extremely difficult. Without adopting the exclusive use of the 

 expression Ophiacantha for all the cases, as has been done by H. L. Clark, I shall 

 often adhere to that expression, putting between brackets the name of the section 

 proposed by Verrill, in order to give some restriction to the rather extended meaning 

 of the first name. 



OPHIACANTHA ACULEATA Verrill. 



Plate 11, figs. 1-2. 



Ophiacantha aculeata Verrill (85), p. 547. 

 Ophiacantha aculeata Verrill (99), p. 36. 

 Ophiacantha aculeata Verrill (99a), pp. 323 and 335. 



Albatross station 2105. Nov. 6, 1883. Lat. 37° 50' N.; long. 73° 03' 50" W.; 

 1,395 fathoms; glob, oz.; temp. 41° F. Seven specimens. 



I have been able to confirm my identification by comparison with a specimen 

 determined by Verrill and coming from station 2725 (lat. 36° 34' N.; long. 73° 

 48' W.; 1,374 fathoms), and which was lent me by the National Museum. I beg 

 to point out, on this subject, that 0. aculeata was described by Verrill in 1885 from 

 some specimens from stations 2034 (depth 1,346 fathoms) and 2105. The speci- 

 mens which were sent me without a name come from the latter station. 



In Verrill's cotype the diameter of the disk is 12.5 mm. Five out of seven 

 specimens which I have studied have analogous dimensions, the diameter of the 

 disk ranging between 12 and 14 mm.; two others are a little larger and their 

 diameter reaches, respectively, 15 and 17 mm. The arms, winch are generally 

 incomplete, may be very long; in the specimen with the disk 15 mm. wide, one of 

 the arms, which is entire, exceeds 90 mm., and Verrill states the length of the arms 

 to be 110 mm. 



VerriU's description is rather short and does not mention certain characters, 

 such as the shape of the upper and under bracliial plates, etc.; and as it is not 

 accompanied by any drawings, I feel sure that it would not permit of identifying 

 the species with certainty . I therefore tliink it best to describe the latter in a more 

 complete manner and to reproduce at the same time a few photographs of the most 

 characteristic specimens. 



The outline of the disk is rounded. The convex upper face is covered with 

 rather short stumps two or three times longer than wide, the surface of wliich is 

 rough or even displays fine rugosities, and the end of which bears a few short and 

 diverging spinules. These stumps, wliich are thick-set, all reach the same height; 

 they are scattered uniformly over the surface of the disk and they completely hide 

 the outline of the underlying plates; they abo cover up the radial shields which are 



