242 PROC. COTTESWOLD CLUB vol. xiii. (4) 



Locality and Sti'ahim of the Figured Specimen : — 

 Birdlip, Gloucestershire, in the Pea-grit. 

 Date of Existence : — Miirchisonce hemera. 



2. "TEREBRATULA"* POLYPLECTA, 5. ^?/r/^;;/««, sp.n. 



PI. XII., figs. 4—7. 



Dcsci iptio?i. — A gibbous valved, broadly ovate shell; the valves are 

 fimbriate for about one-third from the front margin, which itself is 

 usually thickened, obtuse, and fimbriate. Beak very short and obliquely 

 truncate. 



Distinction: — From T. plicata, J. Buckman, it is an alto- 

 gether smaller shell, the plications begin at a much earlier 

 age and are much more pronounced. From T. fimbria. 

 Sow., it has not the globose form of that species, it is 

 more elongate, its beak is shorter, obliquely truncate, and 

 does not overhang the brachial valve. 



Remarks: — This species is a development of Terebr. 

 p/icata, and occurs at a later date. In that species the 

 plications are rather rare, and are only found as the adult 

 character, and then they are not much developed. In this 

 species the plications begin in early maturity, and in late 

 maturity or senility another character commences, namely, 

 thickening of the margin of the valves without increase in 

 the size of the shell — a character well shown in figs. 6, 7 

 of PI. IV., the plication still being continued. Therefore 

 what is a character of late maturity in Terebr. plicata has 

 become a feature of early maturity in this species, which in 

 late maturity introduces another developmental phase. 



Locality and Stratum : — Notgrove Station, Gloucester- 

 shire, in the Oolite Marl. A good series of specimens 

 has been obtained from this locality ; but the species has 

 not been found elsewhere. 



Date of Existence : — Bradfordensis hemera. 



* Generic separation of the fimbriate from the biplicate Ta-ebratulce would be 

 desirable. 



