CtASTRTOCERAS CTRCUl\rNODOSUM. 100 



of Goftfrinceras Listrri, G. cnrhonariiim, and G. rnriiiiiifuni. These were all veiy 

 servicoablo for comparison ^\■itl^ the Firoda specimens. I am nuich indebted also to 

 Dr. Whet'lton Hind, who sent me, from his large collection of British Carboniferons 

 Fossils, specimens of G. I/istcrt and G. ca'dionarinvi, in different stages of growth. 

 Thns I had ample material for the study of the present R])ecies in its relationship 

 witli those above named. 



Before concluding the description of this species it may not jje out of ])lace to 

 refer briefly to the history of GttHtriorcrns Liafcri. The chief interest of this centres 

 in the question, which I had the opportunity lately of discussing with Dr. Hind, as 

 to whether the species figured by Martin (18<>i') under the name " Ammonites 

 Listeri " is the same species as the one afterwards figured by J. de C. Sowerl)y 

 (1825) under the same name. The specimen figured by Martin is lost, therefore 

 only the description and figure are available as evidence ; the latter is decidedly 

 unsatisfactorj', and would only rejiresent very roughly the cliaracters of the 

 ornamentation of the shell now known as Gastrioromf! Listeri. 



Another diffculty is that Martin always describes his species as occiu-ring " in 

 limestone tracts," and associates it with the species (of many of which he was 

 himself the author) commonly occurring in, and characteristic of, the Mountain 

 Limestone. It is well known that (hi>(frincrras Listeri, as universally recognised, 

 belongs to formations of higher horizons than the latter, extending upAvards to the 

 Coal Measures. 



Therefore, if Martin's name Lixtcri is still to be employed, it nnist l)e with the 

 understanding that he was in error as to the horizon of his species. Though it is 

 im])ossible to ascertain the exact locality whence Martin obtained his figiu'ed 

 specimen and others — for he recognised the species as common, — the locality he 

 vaguely referred to as " near Eyem [or Byam] and Middleton " must have included 

 rocks other than the Mountain Limestone, because, according to all experience, 

 G. Lifitori is not found at so low an horizon. It seems in the highest degree 

 probable that the conjecture as to the sti'atigraphical origin of Martin's figured 

 specimen quoted in the foot-note l)elow is correct.' 



In concluding these observations I may draw attention to a point which, how- 

 ever trifling it may seem, is worthy of note, namely, that in the hand-colouring of 

 Martin's figure gold has been useil to ri'preseut iron pyrites, a mineral of conniion 



' Dr. Wheoltoii Hind, witli diaracteristic cnlhiisiasm, iiiiulc a juiii'iicy to ?]yaiii ami MiilclU'ltui in 

 April of this year (1J)03) to fiud out what i-ocks occur at tho-so places, aud he wrote to me ^'iviug me a 

 sketch of the section there, showing tlie Mountain Limestone and the Peudloside Series in connection 

 with it. "The Peudleside Series," he said, " contains thin black limestones in which G. Listeri occurs 

 at other localities, so that it is probable the specimens [Martin's] were obtained from tiiese beds, 

 which were extensively worked in past years for lead veins which traversed them. 'J'liese IxmIs are 

 above the Yoredale Series of Wenlevsdale, in which G. Listeri has never vet been found," 



