944 MR. T. H. WITHERS ON 



T. tuherculata has since been recorded by J. Kafka (1886, 

 p. 565) from the Cenomanian of Kamajk, Bohemia, and by 

 A. Peron (1888, p. 269) from the Turonian of Yonne, France. 

 Kafka mentions a single tergum only, and if his figure is accurate, 

 it differs in certain characters from the original tergum from. 

 Charing. Peron recorded a small and a very large carina., but 

 gave neither measurements nor figures ; he drew attention to the 

 fact that Dtii'win had supposed the species to come probably from 

 the Upper Chalk, and said that so far as he knew it came from 

 the Turonian. 



T. tuherculata occurs fairly commonly in the Cenomanian Chalk 

 Marl near Cimbridge, and we have over 150 valves, including 

 22 valves of the lower whorl. From the Turonian Terehratulina- 

 zone at Whyteleafe, Surrey, we have a single scutum, and from 

 the Cenomanian Chalk Marl of Burham, Kent, a single rostrum. 

 Type. — Tiie collection of the late Mr. Wm. Hariis from the 

 Chalk detritus of Charing, Kent, was acquired from his daughter 

 in 1881, by the British Museum (Natural History). Several 

 valves of T. tiiberculata are represented in the collection, three 

 of which — a carina (I. 14657), scutum (I. 14659), and tergum 

 (I. 14658) — are mounted together on paper, and with them is a 

 label bearing the name " S. tuberculatum " in Darwin's hand- 

 writing. These are probably the original specimens figured by 

 Darwin, but. there is no means of proving this since Darwin gave 

 no measurements of the figured valves of this species. A further 

 label (not in Darwin's handwriting) bearing the words " very 

 valuable " was with the specimens, but whether this was meant 

 to indicate that they are Darwin's original specimens must be 

 left to individual opinion. I consider them to be the types, and 

 since Darwin regarded the carina, as the typical valve in Scalpellum, 

 that valve is here taken as the holotype. 



Measurements. — The valves of this species are exceedingly 

 small, and to judge from these, the largest capitulum could not 

 have measured much more than 5 or 6 mm. in length. Of the 

 upper series of valves the largest examples measure respec- 

 tively : — 



Carina, I. 15850. Length 4-1 mm. ; breadth 1*2 mm. 

 Scutum, I. 15843. Length (from apex to middle of basal 

 margin) 2"5 mm. ; breadth 2"6 mm. 



Tergum, I. 15851. Length 4'3 mm. ; breadth 2"6 mm. 

 Distribution. [? Cenomanian] Chalk detritus : Charing, Kent ; 

 Cenomanian, Chalk Marl : near Cambridge, and Burham, Kent ; 

 Cenomanian, Korytzaner Schichten : Kamajk, Bohemia; Turonian, 

 Terebratulina-zone : Whyteleafe, Surrey ; Holaster planus-z.one : 

 Armeau and Saint-Julien-du-Sault (Yonne), France. 



Description of Valves. — Valves plainly ribbed longitudinally ; 

 the ribs are narrow, but become more prominent on the edge of 

 each zone of growth, where the ribs are thicker and usually stand 

 out as shoi-t blunt spines. 



Carina (PI. XCV. fig. 1) very narrow, either slightly bowed 



