78 BRITISH CARBONIFEROUS BRACHIOPODA. 



jida, Lamarck, (figs. 15, ]6, 17). Sowerby states that "the produced beak and tbree-angu- 

 lar-sided front give the shell a five-angled contour, although the sides are rounded." In the 

 degree of convexity of its valves, different specimens vary to a very great extent, and it ha 

 appeared to me probable that the Terebratula amhigua of Phillips, " pentagonal, depressed, 

 surface undulated, front and sides emarginate, perforation of the beak minute," (fig. 25,) 

 is only a more flattened condition of Sowerby's species. (?) 



Atrypa sublobata, Portlock, has already been correctly identified with Sovs'erby's 8p. 

 ambipius, for it is stated by Professor M'Coy, at p. 432 of his 'British Palaeozoic Fossils,' 

 " I have at length succeeded in tracing, in the most gradual manner, the passages of all 

 the forms figured by General Portlock under the name of Atrypa sublobata, into each other, 

 and in the ordinary types of the present species. When decorticated, a few straight pallial 

 ridges are seen near the beak, radiating towards the front margin. General Portlock 

 notices the resemblance of some of the varieties to 8. unguiculm of Sowerby, but the want 

 of area between the beaks and hinge-line separate the species." It is also possible that 

 Atliyris trilobata, M'Coy, may require to be added to the synonyms of Sowerby's species, 

 but from such insufficient data as the simple dorsal valve represented in Tab. XX, fig. 21, 

 of the ' Synopsis,' it would be hardly safe to offer any decided opinion. 



The presence of spiral appendages in this species did not escape the observing eye of 

 Sowerby, who in 1822 appears to have even hinted at the propriety of establishing a new 

 genus for its reception, for we find him stating, that " in general appearance it does not 

 agree with most species of Sjnrifer, but approaches nearer the smooth Terebratulae ; its 

 having a perforated beak, and little or no hinge-line, still further distinguishes it ; but the 

 actual existence of spiral appendages seems to confirm it a Spirifer, unless its combining 

 the characters of b oil l genera should render it desirable to construct a neio genus of it. But 

 as the appendages within the Terebratulae are very variable, it will be well to wait until more 

 of them are known. "^ 



I have been informed that it was for the reception of T. ambigua and other similarly 

 organised forms, that in 1841 Professor Phillips created his C/e/o/>^ym, which he described 

 with a " cardinal area obsolete, beak incurved over a minute perforation, which is often 

 obtect, or merely serves to receive the beak of the smaller valve ;" but as the author inad- 

 vertently and unfortunately omitted to mention any known species as an example. Professor 

 M'Coy subsequently proposed the name Athyrii for similar kinds of shells. 



^ Professor de Koninck remarks, at p. 297 of his ' Animaux Fossiles de la Belgique,' "that the spiral 

 arms are formed of nine or ten coils, and are placed in an opposite direction ; that it is solely on this 

 last character, which is nevertheless common to many species of Terebratulae, that Mr. De Buch has relied 

 for expressing the opinion that T. amhigua and some others must be placed among the Spirifers, and 

 insinuates at the same time that the circular foramen might perhaps not be the work of nature. We can 

 affirm that this aperture is not due to chance, and that it is to be found on all well-preserved examples; 

 moreover, that Mr. Deshayes builds upon the characters of this species to combat the establishment of the 

 ■genus Spirifer, to which Sowerby had at iirst referred the species." 



2 Sowerby's Sjnrifer amhujuus has received no less than six different generic appellations — Spirifer, 



