E. Westlake — Terebratula from the Upper Chalk. 313 



Mr. Thos. Davidson, who examined them, wrote to me, 28th Feb. 

 1884 — "These specimens are peculiar and puzzle me. They are not 

 T. carnea, nor T. semiglobosa, and I am uncertain as to their proper 

 identification. They approach most in shape to some specimens of 

 Ter. semiglobosa, but I would not like to refer them to that species. 

 They almost look to me a new species." 



1 1« 2 2a 



Terebratula obesa, Sowerby, var. cuneata. 



Enlarged about nine-tentbs natural size. The figures are photo-facsimiles. The 

 fine surface -marking is due to the process employed (Dallastint). 



Dimensions — Fig. 1. length 23-9, width 19-1, depth 10-2, foramen 1-6 mm. 

 Fig. 2. „ 26-2, ,, 19-8, „ 11-2, „ 1-6 „ 



Shell obtusely pentagonal, elongated, depressed, slender and thin ; 

 dorsal valve nearly flat ; beak projects -8 mm. in front of the 

 deltidium, stands off from the dorsal valve -5 mm., and is obliquely 

 truncated by a circular edged foramen 1-6 mm. in diameter. The 

 pieces of the deltidium are about -5 mm. in width. Front margin 

 very slightly undulated. 



In the British Museum are twelve specimens of " Terebratula obesa, 

 Sow., from Greenhithe," (B. M. 20289) identical with the above, 

 excepting that the dorsal valves of the B. M. specimens are rather 

 more convex. The Chalk of Greenhithe contains M. coranguinum 

 and EcMnoconus conicvs. From this zone in Hampshire 1 have 

 about a thousand Terebratulee, all of which, however, are referable to 

 T. semiglobosa or T. carnea. I have not yet met with T. obesa in the 

 Hampshire Basin. 



Affinities and Differences. — Their large foramen and flattened 

 dorsal valve include them in the Ter. biplicata group, which is repre- 

 sented in the Middle and Upper Chalk by T. obesa. With this species, 

 and more especially with the large form from the Norwich Chalk, 

 the specimens figured agree in most respects. They differ chiefly in 

 their flatter dorsal valve and in the absence of lateral plaits, both of 

 which may be characters of young shells. On the other hand, the 

 same form having occurred elsewhere on the same horizon, it maybe 

 convenient to distinguish them as a variety. They differ from T. 

 CipJyensis, von Hanstein, by their thiner shell, flatter dorsal valve, 

 more recurved beak, and smaller foramen. 



