32 DE. T. DAVIDSON ON EECENT BKACHIOPODA. 



arrauulated. . . . the tubules radiate from the larsjest diameter of the caeca, and not from 

 the periphery of the granulated disk, and this is in accordance with the admirable obser- 

 vations made by King *. The scales do not appear to encroach upon the walls of the 

 caeca." 



Then follow many very important details on the growth of the shell, as well as the 

 gradual development of the crura and loop. The crura of the calcareous loop, although 

 not connected by a calcareous shelly layer in the young animal at all stages, have 

 portions nevertheless connected by a membrane charged with spicula. The peduncular 

 opening also, with age, becomes more circular, while the cardinal process, which does 

 not appear in the earlier stages, is latterly present. 



In Prof. Morse's memoir in question a vast number of important details are 

 given, to which we have only briefly alluded. 



I have myself examined specimens at all stages of growth, brought home by the 

 ' Challenger ' Expedition, and I am able to confirm Prof. Morse's accurate observations. 

 When half a line in length the dorsal valve is elongate semicu-cular, the hinge-line 

 straight, and nearly as long as the breadth of the shell, only eight or nine rounded ribs 

 ornamenting the surface of each of its valves ; by degrees the hinge-line becomes shorter 

 and obtusely angular, and the ribs that ornament the surface of the valves become more 

 numerous. 



14. Terbbratulina Wyvlllii, Davidson. (Plate III. figs. 1-3.) 



TerebratulinaWyvilli, Davidson, Proc. Roy. Soc. vol. xxvii. p. 436, 1878, and [T.ivyvilii) Report on the 

 Bracliiopoda, Voyage of H.M.S. 'Challenger/ Zoology, vol. i. p. 32, pi. i. figs. 1-2, 1880. 



SheU large, trigonal, longer than wide, broadest anteriorly, light yellowish; dorsal 

 valve triangular, anterior angles rounded ; hinge-line obtusely angular, moderately 

 convex, somewhat flattened along the middle, and abruptly bent inwards close to the 

 margin; lateral sides of the umbo auricular; ventral valve convex, deeper than the 

 opposite one, flattened anteriorly, abruptly bent inwards close to the margin ; beak 

 incurved, truncated by a large oval-shaped foramen, separated from the hinge-line by a 

 triangular concave depression sharply defined laterally ; surface of shell nearly smooth 

 to the naked eye, but marked by very fine radiating raised lines ; perforations rather 

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

 by the tmion of the oral processes. Length 2J inches, breadth 2 inches, depth 1 inch 

 4 lines. 



Mab. A single specimen of this fine species was dredged on the 25th of March, 1873, 

 by the ' Challenger ' Expedition off Culebra Island, to the north-west of St. Thomas, in 

 the West Indies, depth 390 fathoms. It was also obtained in some abimdance by the 

 Erench expeditions of the ' Travailleur ' and ' Talisman ' in 1882 and 1883, near the 

 western coast of Africa. It is alluded to by Prof. A. Milne-Edwards in the ' Comptes 

 Rendus de 1' Academic des Sciences,' tom. xciii. Nov. 1881, and has also, according to 

 Dr. P. Eischer, been dredged off the coast of Spain. 



* " On the Histology of the Test of the Class Palliobranchiata,"' Traus. Royal Irish Academy, vol. xxiv. 



