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



Carina simply bowed, with the roof flat; the roof does not increase much iu width from 

 the apex towards the base ; rather short, its base being at a considerable distance from 

 the peduncle. The sides of the valve are much narrower in the undermost part than 

 near the apex. 



Upper lut ns trapeziform, in consequence of the shortness of the carina! margin 

 almost triangular ; umbo at the slightly projecting apex, scutal margin concave, basal and 

 tergal margins almost straight. 



Rostral lotus irregularly quadrangular, with the umbo slightly projecting over the 

 occludent margin of the scutum. Rostral margin short, lateral margin slightly 

 arched. 



Infra-median lotus elongate-triangular, with the umbo at the apex, which is slightly 

 bowed towards the rostral side. 



Carina! lotus irregularly rhomboid; the carina! margin has a short upper part, which is 

 concave for the reception of the carina, and a convex and rather long lower part ; the basal 

 margin is very short. The umbo is at the base of the carina above the middle of the 

 carina! margin, it is slightly projecting beyond the carina ; the inferior parts of the carina! 

 niaro'ins of the two carina! latera touch each other in the middle below the base of the 

 carina, The carina! latus is divided into two triangular parts by a ridge running from 

 the umbo to the angle near the apex of the infra-median latus. 



Length of the capitulum, 18 "5 mm. 



Peduncle cylindrical, slightlv bowed, and of considerable length (9 mm.). The scales 

 a tv nut very distinct and rounded at their free edge. There are seven longitudinal rows, 

 each containing more than twelve scales. 



I have in it studied the structure of the animal within the capitulum. I have 

 found one complemental male at the place it ordinarily occupies. It is rather large, 

 1 icing 1'8 mm. long, and it shows the structure of the complemental males of most 

 of the deep-sea species. Its surface, however, does not show the little spines which 

 ordinarily invest it. The receptaculum seminis was filled with thread-bke spermatozoids. 



This species was taken at Station 184, August 29, 1874 ; lat. 12° 8' S., long. 145° 10' E. ; 

 depth, 1400 fathoms; hot torn temperature, 1°"8 C. ; bottom, grey ooze. 



Observations. — In this species the form of the carinal latus is highly characteristic. 

 The ridge, which runs from the umbo to the point where the infra-median latus and the 

 upper latus touch each other, divides the valve into two parts. The part which is placed 

 beneath the ridge in shape almost entirely resembles the whole valve in Scalpellum 

 regiwm ; by the presence of the other part the valve, however, more resembles the same 

 valve in Scalpellum triangulare, Scalpellum brevecarinatwm, and others. Among the 

 species of Scalpellum which have the carinal latus as in Scalpellum regium, and the valve 

 as in the present species, Scalpellum velutinum (PI. IV. fig. 10) may be placed; in this 

 species the carinal latus sin >ws a small triangular part between the ridge and the upper latus. 



