DE. T. DAVIDSON ON KECENT BRACHIOPODA. 117 



divaricator, and ventral adjusters in the ventral valve have been well defined by Wood- 

 ward, at page 218, fig. 118, of his 'Manual of the MoUusea.' 



Hah. Rio de Janeiro, 13 fathoms (Macgillivray) ; bleached dead shells can be picked up 

 on the beach on the open coast just outside the mouth of the Bay of Rio, but generally 

 much worn and imperfect (Derby). 



Ohs. The animal of this beautiful small species has not been hitherto examined. The 

 shell varies very little in shape and character ; its internal details are difiicidt to describe 

 in words, but a glance at the figures will make all clear. The shell has been described 

 under the specific names of Terehratula rosea, T. tulijM, T. unyuls, and, I believe, T. ttdipa 

 rosea. Some uncertainty has also prevailed with respect to the name first published. 



The form was well figured in 1823 by Mawe under the appropriate specific name of 

 rosea, some years before that of tuUpa, given to it by Blainville in 1828. Mawe 

 appears to have adopted names chiefly from the manuscripts of Ilumphrey, Da Costa, 

 and Solander, and several authors have taken the name rosea from Humphrey. 



In 1849, noticing the great dissimilarities the species presented in its internal structure 

 from other Terebratulida^, I proposed to create a distinct genus for its reception, and gave 

 it the name of Bouchardia, which has been very generally adopted since that period. 

 Lovell Reeve, in his monograph on Terehratula, expresses himself to the efi'ect that 

 T. Cnmhiffi, T. fihda, and T. rosea are distinguished from all other Terebratulae by the 

 structure of the beak of the shell. 



At my request INIr. John Yomig, of the Hvinterian Museum, Glasgow, carefully 

 examined the shell-structure of Bouchardia rosea and Magasella Cumingi ; he wrote me 

 on the 20th of April, 1885 :— 



" I have carefully etched the valves of both sj)ecies, so as to reveal more clearly the 

 nature of these perforations. Both species have their shell-structure perforated after the 

 same manner ; but there are some differences in the perforations and in th(> shell-structure 

 between the pores, which I will notice further on. Before etching, I examined both the 

 outer and inner surface of the valves, to see what was revealed, and noted what I saw. 

 In Bouchardia rosea the outer surface showed numerous minute oval punctures. The 

 inner surface showed only punctures on the thinner portions of the valve near the margin, 

 more towards the beak. 



" In Macjasella Cnm/i/r/l the outer surface on both valves showed numerous minute oval 

 pores. These were most distinctly seen around the margin of the valves. On the inner 

 surface of the ventral valve the punctures are only faintly seen. On the inner surface of 

 the dorsal valve the punctures are not visible except by transmitted light ; they can be seen 

 passing downward through the shell-structure. After etching the shells to a greater trans- 

 parency the perforations become much more distinctly seen on the outer surfaces of both the 

 valves. In Bouchardia rosea they appear to be smaller and a little more numerous than 

 in M. Cmninffi. The tubes in their upward passage through the structure of the shell are 

 seen to be always inclined and directed towards the beak, and these tubes increase in 

 diameter as they open on the surface, agreeing in this resjject with what has been already 

 recorded. With a 1-inch or i-inch power of the microscope, imder a strong beam of 



16* 



