DR. T. DAVIDSON ON EECENT BEACHIOPODA. 39 



portions of the umbo are decidedly auricular, and the character ol' the radiating 

 riblets would, he thinks, warrant us in classing the shell in the last-named subgenus. 

 It appears to be a good species. 



23. Terebkatulina Mtjrrati, Davidson. (Plate VI. figs. 15-17.) 



Terebratvla Murrayi, Davidson, Proc. Roy. Soc. vol. xxvii. p. 437, 1878; and {Terebratulina murrayi) 

 Report of the Braehiopoda, Voyage of H. M.S. ' ChaUengcr,' Zoology, vol. i. p. 39, pi. i., 1880. 



Shell small, obscurely trigonal, about as broad as long, widest anteriorly, tapering 

 posteriorly, white ; surface of valves marked with about seventeen rounded ribs, of which, 

 in some specimens, a few are due to the interpolation of smaller and shorter ribs between 

 the longer ones, the whole surface crossed also by fine concentric lines of growth. 

 Hinge-line obtusely angular. Ventral valve a little deeper than the dorsal one, beak 

 very slightly incurved, foramen rather large and incomplete, margined laterally by small 

 deltidial plates. In the interior of the dorsal valve the loop is simple. Length 2, 

 breadth 2 lines. 



Hah. Dredged by tin; ' Challenger' Expedition in 1871, lat. 38° 35' S., long. 177° 50' W., 

 near Kermadoc Island, soutli of Fiji Islands, in a depth of 600 fathoms. 



Obs. .Some eleven examples of this small shell were dredged by the ' Challenger ' 

 Expedition, and none exceeded the dimensions above given. It varied a good deal with 

 respect to the character of its ribs ; in some they were all simple, while in others smaller 

 and shorter ribs were interpolated here and there between the longer ones. The crura 

 likewise in some examples in the younger individuals were disunited. In 1879 I sent a 

 specimen to Mr. Dall for examination, and he wrote me, saying that " by devoting about 

 half an hour to this little shell, I have cleared away all the animal matter, leaving the loop 

 perfect. You will see at once that it is a young Terehratidimi. I suspected this before 

 I could see the loop, from the character of the punctuations, which, you will recollect, is 

 peculiar to the group." I had also previously ascertained that the loop is simple, and 

 that the mantle rises from the bottom of the shell near the loop and adheres to its sides, 

 as was so well illustrated by E. Deslongchamps in TerehratiUina caput-serpentis. 



21. Terebratulina tuberata, Jeffreys, sp. (Plate VI. figs. 18-20.) 



Terebratula tuberata, Jeffreys, MoUusca of the ' Lightning' and 'Porcupine' Expeditions, 1868-70, 

 Proc. Zool. Soc. 1878, p. 401, pi. xxii. fig. 2. 



Shell somewhat triangular, broadest and rounded anteriorly, tapering posteriorly, 

 longer than wide. Dorsal valve semicircular ; hinge-line nearly straight, shorter than 

 the Avidth of tln^ shell ; vahe moderately convex and somewhat compressed, lateral sides 

 of umbo auricular. Ventral valve rather deeper than the dorsal one; beak pointed, very 

 little incurved ; area triangular ; foramen oval-shaped and incomplete, margined anteriorly 

 by the umbo of the ventral valve, laterally by small deltidial plates. Surface of valves 

 traversed by about twenty radiating ribs, of which some are shorter and interpolated 

 between the longer ones. Valves crossed likewise by numerous equidistant concentric 

 raised lines, sometimes slightly projecting and prickly in the young. In the dorsal valve 



