106 THE VOYAGE OF H.M.S. CHALLENGER. 



sided, outer edge straight, lateral corners much rounded, and an angle inward; length 

 to breadth '8:1. Side mouth shields squarish and large, widely separated by mouth 

 shields, similar in form arid position to the side arm plates beyond. First under arm 

 plate small triangular, with an acute angle inward, and outer edge slightly curved ; 

 second plate four-sided, wider without than within ; third plate as long as broad, much 

 wider without than within, having outer corners rounded. All the plates are apparently 

 composed of two pieces, — an inner, which has a sharp angle outward, and an outer, which 

 comprises the rest of the plate. Side arm plates broad, not swollen, meeting neither 

 above nor below. Upper arm plates wider without than within, considerably arched, 

 and with outer corners prolonged in small peaks. Disk round and thick, covered above 

 and below with very minute granulation, 15 or 20 grains in the length of a millimetre. 

 Radial shields small, of a rounded pear-seed shape, nearly or quite joined, and to be 

 seen only when the granulation has been removed. Genital openings extending from 

 outer edge of mouth shield to margin of disk. Genital scales hidden by the skin 

 and granulation. On the interbrachial edge of the side mouth shields are four short 

 rounded papillae. Three long, very delicate, pointed arm spines, the middle one a little 

 the longest, upper and under spine of about the same size, and about as long as an 

 arm joint. One long pointed tentacle scale on each of the first pair of tentacle pores ; 

 beyond there are two, one large and rounded, and one smaller and narrower. Colour in 

 alcohol, white. 



The description is from a specimen larger than the one figured. 



A smaller specimen (Station 24) was more evenly granulated, and the radial shields 

 were quite hidden. The upper arm plates were so thin as to show the arm bones 

 through. 



Station 24. — March 25, 1873; off Culebra Island; 390 fathoms; mud. Station 

 33.— April 4, 1873 ; off Bermudas ; 435 fathoms ; mud. Station 23.— March 15, 1873 ; 

 off Sombrero Island ; 450 fathoms ; globigerina ooze. 



Ophioconis. 

 Ophioconis, Ltk., Addit. ad Hist., part 3, 1869. 



Entire disk, including more or less of the mouth angles, covered by a close and fine 

 granulation. Numerous (7-9), slender, hollow arm spines. Numerous (10-14) small 

 close-set mouth papillae to each angle. Teeth. Few or no tooth papillae. Two genital 

 openings in each brachial space. 



A general delicacy of structure characterises the skeleton (Ojihioconis miliaria) 

 including the disk scales which are small and thin, and the radial shields which are small 

 and separated. Genital plate rather weak, and flattened, with a slightly clubbed head, 

 and a thin genital scale attached at some distance inward. The mouth frames, which 



