26 DR. T. DAVIDSON ON EECENT BRACHIOPODA. 



willing to assert that the specimens he has seen seem distinguishable, and that as the dis- 

 tribution of the two forms is absolutely separate, their identity would seem to require proof. 



12. Terebratulina. Cailleti, Crosse. (Plate V. figs. 41, 42.) 



TerebratuUna Cailleti, Crosse, Journ. de Conch, vol. xiii. p. 27, pi. 1. figs. 1-3, 1865 ; Pourtales, Bull. ^lus. 

 Comp. Zool. (Harv.) vol. i. p. 109, 1867 ; Dall, Am. Journ. Couch, vi. p. 106, 1870, and Bull. Mus. Comp. 

 Zool. (Harv.) vol. iii., 1871 ; Davidson, Report on the Brachiopoda, Voyage of H.M.S. Challenger,' 

 Zool. vol. i. p. 37, pi. 2. fig. 2, 1880; Dall, Bull. Mus. Comp. Zool. (Harv.) vol. ix. p. 103, 1881. 



Shell ovate, longer than wide, broadest about the middle, rounded or slightly indented 

 in front ; dorsal valve evenly convex, no defined mesial fold, lateral sides of the umbo 

 auricular ; ventral valve moderately convex, with a strongly marked longitudinal depres- 

 sion or sinus, commencing at the beak and extending to the front ; front raised into a 

 rounded wave ; beak short, and obliquely truncated by a moderate-sized incomplete 

 foramen and two small disunited deltidial plates ; surface of valves marked with about 

 forty small radiating riblets, the larger number being shorter ones interpolated at various 

 distances between the larger ones ; surface marked also with fine concentric raised lines. 

 Loop short, crura disunited in the young, annelliform in the adult. Colour of a slightly 

 greyish white. Length 5, breadth 4, depth 2 lines ; but Mr. Dall mentions having taken 

 specimens 1 inch in length. 



Hab. T. Cailleti was obtained by M. de Pourtales off Chorrera, Cuba, in 270 fathoms ; 

 near Cojima in 450 fms. Off Double-headed Shot Key in 471 fms., and near Tennessee 

 Eeef in 115 fms. Ofi" West Florida 30 fms., St. Vincent 88 fms. (Pourtales and Dall). 

 At Guadaloupe in 200 fms., by an Italian party who were searching for beds of coral. 

 Mr. A. Agassiz sent me a specimen dredged by the Hunter Expedition off Barbados, taken 

 at a depth of 100 fms., and I have also two young examples dredged by L. Barrett off 

 Jamaica, and by Sigsbee off Havanna, in from 80 to 450 fms. I am likewise indebted to 

 Mr. E,. Bathbun for several young specimens obtained in 70 fms. in lat. 21° 48' S. and 

 long. 40° 3' W. of Greenwich, which had been dredged by the Captain of the English 

 Atlantic steamer ' Norseman.' A single example was obtained by the ' Challenger ' 

 Expedition, west of Pernambuco, in 350 fathoms. 



Obs. This species has been minutely described by Mr. H. Crosse and by Mr. W. Dall. 

 Crosse says that it is easily distinguishable from T. caput-serpentis by its stronger radi- 

 ating riblets, these last being more separated from each other than in Linne's species. 

 When quite young, and measuring 1 line in length, it has only from nine to ten simple 

 ribs ; at 2 lines abeady two or three short interpolated riblets have made their appearance 

 close to the margin ; at 3 lines in length the interpolated riblets become more numerous, 

 and the whole surface is concentrically crossed by strongly marked, slightly projecting, 

 equidistant, concentric ridges. Tiie ridges become very much less marked as the shell 

 aj)proaclies and attains the adult condition ; but this feature is common to several species 

 of the subgenus. 



usual, and more or less cloven in front " (" Mollusca of the ' Lightning ' and ' Porcupine ' Expeditions," Proc. Zool. 

 Soc. 187S, p. 401). From a MS. note attached to the types in the Davidson Collection, it is evident that Dr. Davidson 

 considered this to be " a good variety of T. caput-serpentis," but identical with the sheU named Terebratula 

 I'maiyinata by Risso in 1826, " of which the Terehratula <piadrata, Risso, is probably a synonym." The variety 

 mediterraneci should therefore be henceforth known as T. caput-scrpentis, var. eniargiiuita, Risso. — A. C] 



