REPORT ON THE BRACHIOPODA. 33 



Terehratulina caput-serpentis, Lin., var. septentrionalis, Coutliouy (PI. I. figs. 3-9). 



Terehratidina sc2Jtentrlonalis, Coutliouy, Best. Jour. Nat. Hist., vol. ii. p. 65, pi, iii. fig. 18, 1838 



or 1839. 

 Terehratulina septentrionalis, Sow., Tlies. Couch., p. 344, pi. xviii. tigs. 5, 6, 1846. 

 Terehratulina septentrionalis, Stimpson, Test. MoU. New England, p. 75, 1851. 

 Terehratulina capvt-serpe7itis. Reeve, Mon. of Terebratula. Conch. Icon., 1861. 

 Terehratulina se}ytentrionalis, Morse, On the Early Stages of Terehratulina septentrionalis, Mem. Bost. 



Soc. Nat. Hist., vol, ii. 1869. 

 Terehratulina septentrionalis, Gould's Invert. Mass., p. 208, 1867, and Binny's 2d edit,, p. 208, fig, 



500, 1870. 

 Terehratulina septentrionalis, Dall, Cat. of Recent Species of Braohiopod, Proc. Phil. Acad. Nat. 



Sciences, p. 180, July 1873. 



Shell rather thin longitudinally, broadly obovate, pear-shaped or somewhat penta- 

 gonal, narrow and tapering posteriorly, abruptly widening below the beak, broadest 

 anteriorly ; front-hne either nearly straight, slightly indented, or rounded. Colour 

 yellowish-white, nearly diaphanous. Dorsal valve gently convex, most so about the 

 middle, slightly depressed towards the front, eared at the umbo. Ventral valve feebly 

 convex or slightly deeper than the dorsal one, somewhat depressed towards the front. 

 Beak short, attenuated, slightly incurved and truncated by a moderately large and in- 

 complete semi-elliptical foramen completed below by the umbo of ventral valve and 

 laterally margined by small deltidial plates. Surface of both valves covered with a 

 variable number of fine rounded radiating striae (240 in some specimens when counted at 

 the margin). These increase in number by numerous intercalations of shorter ribs at vari- 

 able distances from the beaks. Eibs few, simple and stronger in the young shell. Valves 

 crossed or decussated by fine concentric lines of growth. Shell structure perforated by 

 numerous small canals. In the interior of dorsal valve the loop is short and simple, 

 rendered annular by the union of the oral processes. Brachial appendages united to each 

 other by a membrane, cirrated and developed from each side of the mouth, divided 

 into three lobes, the two lateral ones extending to a little more than two-thirds of the 

 length of the valve, the central one not exceeding half the length of the valve, 

 spiral at its extremities (fig. 5). Proportions variable. Length 27, breadth 21, depth 

 12 mm. 



Habitat. — The geographical range of the variety septentrionalis seems to l^e very 

 great. The Challenger Expedition dredged it abundantly off" the New York coast on 

 May 3, 1873, at Station 48, lat. 43° 2' N., long. 64° 2' W., at a depth of 51 fathoms. 

 Sea bottom, rock (PL L figs. 4, 5). Also on May 20, 1873, at Station 49, lat. 43° 3' N., 

 long. 63° 39' W., at a depth of 83 fathoms off" Halifax. Bottom temperature, l°-8 C. 

 Sea bottom, gravel and stone (PI. L fig. 5). Again, on December 18, 1873, abundantly at 

 Station 142, lat. 35° 4' S., long. 18° 37' E. off" the Cape of Good Hope, associated with 

 Terebratula vitrea, var. minor and Kraussina p)isum in 150 fathoms. Bottom tempera- 



(ZOOL. CHALL, EXP. PART I. 1880.) -^ 5 



