OF CONCHOLOGY. 127 



Subgenus IsMENiA (King), Gray. 



Ismenia, Kii^gi Permian Foss. p. 81, 142 (not Isnienia, King, 



Perm. Foss. p. 245, = TerehrateUa). 

 Ismenia, Gray, B. M. Cat. p. 104. A. Ad. An. Nat. Hist. 



1863, p. 99. 



Shell externally resembling TerehrateUa. Apophyses broad 

 and short, attached first by the septal processes to a short, stout 

 septum, then recurved, the broad posterior edges of the reflected 

 portion touching and blending with the septal processes and the 

 adjacent part of the haemal processes, forming a funnel-shaped 

 ring, into which the septum does not project. The lateral loops 

 of the apophyses remain open in the adult. 



Brachia without a median spiral lobe. 



The name Ismenia was originally founded by an error, (see 

 Perm. Foss. p. 245), upon Terehratulites pectunculus, Schloth. 

 This error Prof. King corrects, as above, stating that his intended 

 type was T. pectunculoides, Schloth. The latter species is only 

 distinguished from the typical TerehrateUce by a few calcareous 

 denticles on the anterior terminations of the lateral loops. Now 

 T. pectunculus has the loop above described as characteristic of 

 Ismenia, as Quenstedt's figure (erroneously referred to by Dr. 

 Gray, in B. M. Cat. p. 95, where the figures of T. jyectimculoi- 

 des are referred to, by the numbers which really refer to T. pec- 

 timoidus, which is on the same plate) shows. 



Dr. Gray, either intentionally or by mistake, thus retains 

 pectunculus as the type in spite of Prof. King's erratum, and the 

 subgenus thus limited will stand properly as of Gray. There 

 can be no doubt as to Prof. King's intentions, as he refers to 

 Davidson's figure of T. pectunculoides in the An. Nat. 1850, pi. 

 XV, fig. 5 a, b. 



Type Ismenia pectunculus (King in err. Per. Fos. p. 81, 142), 

 Gray, B. M. Cat. p. 104 = Terehratulites pectunculus, 

 Schlotheim, Quenst. Handb. p. 466, pi. 37, fig. 23, 25. 



Fossil, Oxford clay, France ; Coral Rag. Germany. 



Ismenia sanguinea, Chemn. sp. PI. 8, fig. 13. 



Anomia sanguinea, Chemn., Conch. Cab. viii, p. 96, pi. 78, 

 fig. 706. DiUwyn, Rec. Shells, p. 293, 1817 (not Sol.) 



Anotnia sayiguinolenta, Gmel., S. N. p. 3347. 



Anomia criienta, Sol. MS. in Mus. Banks (not Dillwyn). 



Terehratula cruenta, Donovan, Nat. Repos. pi. 56, fig. 1. 



Terehratula erythroleuca, Quoy and Gaim, Voy. Astrol. iii, p. 

 557, pi. 85, fig. 8, 9. Desh. in Lam. ed. ii, vii, p. 350. 



