182 BULLETIN OF THE BUREAU OF FISHERIES. 



'I't'rgii large and rhombic, with erect ajiiccs. Tlic iic<-liuient margin is straight, the carinal margin 

 straight aliovc but convex where in contact with llie carina. The scutal margin is nearly straight. The 

 carina is extremely broad basally, the roof convex, the lateral angles prominent. It is cnrx'ed through- 

 out, l>ut the upper half more so; apex terminal. 



The upper lateral plate is triangular, with apical niu'leus. Its scutal margin is longer than either of 

 the other two, which are sube(iual. The rostrum is an excessively small, very narrow plate, visible below 

 the apices of the rostral latera. The rostral lateral plates are low, obliquely triangular, with the apices 

 contiguous at the median ventral line. The lateral edge is covered b)' the imbricating rostral margin 

 of the inframedian lateral plate. The inframedian lateral plates are triangular, nearly equilateral, with 

 apical umbo. The carinal lateral plates are subtriangular, embracing the lateral angles of the carina; 

 their ajiices are recurved and project slightly. The peduncle is covered with horizontal, somewhat 

 imbricating, smooth .scales, which are rather sparsely tomentose, the hairs very delicate and rather long. 

 Its total length is unknown, as the individual has been removed from its support by cutting the peduncle. 



Length of capituhun 25, greatest breadth 16 mm.; greatest thickness, across the carino-lateral plates, 

 12 mm. Length of carina 2L5, diameter at l)ase 9.5 mm. 



Type, no. 32416 U. S. National Museum, from Alhalross .station -1181, near Kauai, in Sll fathoms, 

 bottom manganese sand and globigerina ooze. 



SmI j>ellum rubrum Hoek, from near Luzon, agrees with S. hairaiense in the proportions of the valves, 

 but it differs strikingly in ccJor and surface s(.-ulpture. S. hirsutum is also related, though ob\-iously 

 different. 



Scalpelluni pacificum, n. sp. 



[PI. IV, tig. 3, 4.] 



A form closely related to Scalpelluyn australicum Hoek. 



The capilidum is acutely ovate, compressed, composed of 14 valves closely juxtaposed; these are 

 covered with a very thin brownish film, which near the occludent margin bears a few scattered long 

 hairs. The valves are sculptured with numerous, but not crowded, radiating threads, and on each of 

 the side valves there is one more prominent ridge or angle extending from the umbo to the opposite 

 margin, dividing the valve into two areas. 



The scutum is convex, divided into two nearly equal arei\« by a slightly curved diagonal rilj; the 

 occludent and opposite lateral margins are slightly arcuate, the tergal and liasal margins straight, the 

 latter at an angle of 90 or a trifle less with the occludent border. 



The tergura is larger than any other plate, triangular, with a distinct diagonal rib parting the narrow 

 carinal from the large and triangular anterior area. The occludent margin is convex, the carinal a little 

 undulating and the tergal or basal margin straight. The apex stands erect. 



The carina is simply arched, with the flat roof bordered by distinct ridges; sides at about right 

 angles with the roof, and broader near the upper extremity of th<' valve. 



The upper lateral plate is trapeziform with the apex superior, the scutal margin concave, the liasal 

 and tergal margins equal, straight, and the very .short carinal margin also straight. 



The rostral lateral plate is sid)quadrate, short and liroad, the length being about half the width. 

 The curved beaks are connate on the occludent border above the rostrum, and do not project percep- 

 tibly. The upper and lower borders of the plate are subparallel and straight; the rostral border is 

 concave. From the umbo a curved rib runs to the posterior basal angle. The rostrum is rudimentary, 

 merely a linear trace. 



The inframedian lateral plate is extremely narrow, linear, wedge-shaped, the narrow apex al>ove. 

 There is a low cord along each edge, and the apex is curved rostrad. 



The carinal lateral jjlate is irregularly trapezoidal, with the umbo projecting a little beyond the 

 carina. The carinal margin is straight; upper margin very olilique, straight; lateral margin short, 

 straight. In carinal aspect, the two carinal latera appear as contiguous tricostate brackets under the 

 two lateral ribs of the carina. The peduncle is short, wider above, covered with wide low scales, about 

 seven scales in any longitudinal row. 



Length of capitidum of type, from station 3907, Ki.o mm., greatest breadth 8.5 mm., diameter 3.8 

 mm.; length of peduncle 3.5 mm. 



