28 DK. T. DAVIDSON ON RECENT BEACHIOPODA. 



13. Terebratulina sbptentrionalis, Couthouy. (Plate V. figs. 1-31 & 48-52.) 



Terebratulina septentrionalis, Couthouy, Boston Journ. Nat. Hist. vol. ii. p. 6.5, pi. iii. fig. 18, 1838. 



Terebratula septentrionalis, G. B. Sowerby, Thes. Conch, p. 342, pi. xviii. figs. 5 & G, 18-J.6; Stimpson, 

 Test. Moll. New England, p. 75, 1851. 



Terebratula cujjut-serpentis, L. Reeve, Monogr. of Terebratula, Conch. Icon. 1861. 



Terebratulina septentrionalis, E. Morse (On the early Stages of), Mem. Boston Soc. Nat. Hist. vol. ii. 

 (read Oct. 1869) ; Gould, Invert. Mass., Binney's 2nd ed. p. 208, fig. 500, 1870. 



Terebratulina septentrionalis, Dall, Cat. of Recent Bracli., Proc. Acad. Nat. Sci. Philadelphia, 1873, 

 p. 180; Sars, Fauna Moll. Regiouis Arctics Norvegise, p. 10, tab. i. fig. 4, 1878. 



Terebratulina caput-serpentis , var. septentrionalis, Davidson, Report on the Brachiopoda, Voyage of 

 H.M.S. 'Challenger,' Zoology, vol i. p. 33, pi. i. figs. 3-9, 1880. 



Terebratulina caput-serpentis, W. F. Ganong, The In^'ertebrate Zool. of Passamaquoddy Bay, Nat. 

 Hist. Soc. of New Brunswick, Bull. No. 4, p. 91, 1884. 



Shell rather thin, longitudinally broadly ovate, pear-shaped or somewhat subpen- 

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

 anteriorly ; front line nearly straight, slightly indented or rounded ; colour yellowish 

 white, nearly diaphanous ; dorsal valve gently convex, especially towards 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 incomplete 

 semielliptical foramen, completed below by the umbo of the ventral valve, and laterally 

 margined by small deltidial plates; surface of both valves covered with a variable 

 number of fine rounded radiating raised striae or riblets (240 in some specimens when 

 counted at the margin), these increase in number at variable distances from the beaks 

 by the interpolation of shorter riblets; shell-structure perforated by numerous small 

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

 annular, with age, by the union of the oral processes. The brachial appendages are 

 united to each other by a membrane, cirrated and develoijed 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, 

 and spiral at its extremities. Proportions variable. Length 16, breadth 11, depth 

 6 lines. 



Sab. The geographical range of T. sejjtentrionulis seems to be very extended. The 

 ' Challenger ' Expedition dredged it abundantly olf the New- York coast at depths of 

 61 fathoms, also, at a depth of 83 fathoms, off Halifax. Again, accordmg to the ofiicers 

 of the expedition, ofi" the Cape of Good Hope (but I should like to have this last state- 

 ment confirmed), at latitude 46° 40' S., long. 37° 50' E., at a depth of 160 fathoms. 

 Mr. Couthouy, in his description of T. septentrionalis, says that it has been found at 

 Lubec Bay by Dr. C. T. Jackson during his geological survey of the State of Maine, and 

 that it is proljably an inhabitant of deep water on the whole New-England coast. 

 Dr. Gould mentions having found it in considerable numbers in the stomach of fishes, 

 and occasionally on the sea-beach, and that its usual habitat is in the Laminarian or 

 deep Coral zones of northern seas. At Eastport, at low water, it is common off the 



