390 Mr. S. S. Buckman on Jurassic Brachiopoda. 



young examples, and is sometimes preserved in the adult, 

 but in many cases it has disappeared. 



There are only a few species of the genus, and they may 

 be recorded in the following manner. The method employed 

 is a suggestiou for a palasontological dictionary, to give in 

 the most concise form information concerning types. The 

 symbols employed are : — 



T.d. (Type-description) : Reference to the first description of the 

 species, quoting the original name. T.f. (Type-figure) : Reference 

 to figure of holotype, or what is now selected as holotype out of 

 cotypes. N. (Name): Where the present specific designation was 

 given, in a case of renaming. T.l. (Type-locality) : The place 

 from which tlie holotype or the specimen figured as standard of 

 reference came, so that it may be known what are topotypes, 

 for they are of the greatest importance, next to types, for 

 specific determination. H. Horizon, iu author's words^modern 

 interpretations or corrections in square brackets, t). Hemera. 

 Coll. Collection in which the type specimen was recorded by the 

 author — its present resting-place if different, and known, to be 

 noted in square brackets. 



Genus — Okthotoma, Quenstedt, 1871. 



Genotype, Terehratula heyseana, Quenstedt (non Yi-ankQr)=.OrtJwtoma 



Quenstedti, nom. nov. q. v. 

 K«f. : Petref. Deutschl. ii. p. 315. 



1. Orthotoma anglica (Oppel). 



T.d. 1856. Oppel, Juraf. p. 425 ; Terehratula analica. 



T.f. 1854. Davidson, Ool. & Lias Brach. (PaL Soc.) pi. A. fig. 10 



(figs. 10-13). 

 T.l. Dundry [Somerset]. 

 H. "Inferior Oolite" [Aalenian], 

 77. \3IurcMsonce.\ 

 Coll. Bristol Museum. 

 Emend. : S. Buckman, Dundry Hill, Q. J. G. S. 189G, vol. lii. p. 702. 



2. Orthotoma heyseana (Danker). 



T.d. 1847. Dunker & Meyer's Palaeont. Beitr. z. Naturg. i. p. 129; 



Terehratula heyseana. 

 T.f. Ibid. pi. xviii. fig. 5. 

 T.l. Heiuberg, near Gottingen. 



H. " With Terehr. [It/iynch.} rimosa'' [Pliensbachian]. 

 Syn, Terehratula Bakeries, Davidson. 



Bemarks. — There are two specimens in the Mantell Col- 

 lection at the British Museum, no. 24188, which are 

 topotypes and perhaps metatypes. They have great likeness 

 to Terehratula aspasia, var. mitior, Zittel {Olossothyris) , but 

 they differ in regard to the beak ; that possesses decided 

 ridges which are wholly wanting in the beak of T. aspasia. 



