Zoological Society. 147 



Adams and Reeve principally in the form of its beak and in its 

 coloration ; the Corean form is beautifully strigated with vivid red, 

 while Ter. Bouchardii is of a uniform light yellow colour ; the details 

 of the loop seem likewise to differ a little. 



3. Terebratella Evansii, Dav. 1852. 



Diagnosis. — Shell subovate, longer than wide ; perforated valve 

 most convex, smaller one rather compressed ; beak tapering, not much 

 recurved, and obliquely truncated by an emarginate foramen ; del- 

 tidia small ; beak-ridges well defined, leaving between them and the 

 hinge-margin a false area ; surface ornamented by a few unequal bi- 

 furcated and intercalated costee ; colour pale red ; structure punc- 

 tate ; apophysary system composed of a central longitudinal sep- 

 tum, not exceeding half the length of the valve, arising rapidly in the 

 form of a narrow elevated plate, almost reaching the centre of the 

 perforated valve, to the middle of which, and to the crural base, are 

 doubly attached the calcareous riband-shaped lamellae forming the 

 loop. Length 4, width 3^, depth 1^ lines. 



Hub. New Zealand. Coll. Cuming. 



Obs. — On first inspection, I thought this shell, of which Mr. Cuming 

 has two examples, might be the young of Terebratella Zelandica ; but 

 on examining the calcareous appendages, I found great dissimilarity in 

 their respective details. In Ter. Zelandica the loop is first fixed to the 

 hinge-plate, and again, by a transverse shelly horizontal process, to 

 the extremity of a slightly elevated mesial septum ; the lamella pro- 

 ceeding again before bending back, as in all Terebratellce : but in the 

 interesting little form under notice the mesial septum forms a narrow 

 elevated plate, extending as far and further than the greatest length 

 of the lamellae, which last are fixed to the middle portion of the sep- 

 tum. The remarkable deviation from the general details of the 

 arrangements in this Terebratella has prompted me to examine with 

 care a multitude of specimens of different species belonging to the 

 genus, and I was not a little surprised to find that some few other 

 forms presented a similar arrangement, such as Ter. crenulata, 

 Ter. Cumingii, &c, thus forming a passage into Magas, which last, 

 although generically distinct, can no longer constitute a separate 

 family from the TerebratulidcB. 



4. Terebratella? Cumingii, Dav. 1852. 



Diagnosis. — Shell very thick, ovato-oblong ; larger valve most con- 

 vex, slightly keeled ; imperforated one rather depressed ; beak pro- 

 duced, tapering, not much recurved, and truncated by a small oval 

 foramen, beginning at the summit of the beak, and directing itself on 

 the opposite side to the area ; no visible deltidium ; a concave trian- 

 gular area ; surface smooth, strongly marked by concentric lines of 

 growth ; colour white, or slightly tinged with red ; shell articulating 

 by means of two strong teeth in the larger and corresponding 

 sockets in the smaller valve ; apophysary system very complicated, 

 composed of a mesial longitudinal elevated triangular septum extend- 

 ing to about two-thirds of the length of the smaller valve, and which 



10* 



