NATURAL SCIENCES OP PHILADELPHIA. 277 



liar internal characters of Syringothyris, it becomes a matter of some interest 

 to know upon which of these types Sowerby formed the genus Spirifer. If it 

 was upon the one with a punctate structure and an internal tube, then Syringo- 

 thyris would apparently be an exact synonym of the genus Spirifer, which 

 would differ from the ordinary types usually referred to that genus, such as 

 S. striatum for instance, (= Trigonotreta, group of Koenig, ) as widely as the 

 latter differs from Spirifer in a and Cyrtina. If, on the contrary, Sowerby's 

 type was an impunctate shell without tlie internal characters of Syringothyris, 

 or in other words a Trigonotreta, then Syringothyris would stand as a distinct 

 group, differing from Spirifer proper in as important characters as those dis- 

 tinguishing Spiriferina and Cyrtina. 



Since seeing some of the internal casts of Syringothyris, in Mr. Worthen's 

 collection, showing the peculiar appearances produced by the impressions left 

 by the false deltidium and its attached internal tube, I have been struck with 

 their similarity to the figures given by Mr. Davidson, (on plate ix. of his work 

 already cited), of an internal cast of a supposed example of S. cuspidatus, 

 thought to indicate the presence of a perforation through the deltidium. It 

 is also worthy of note that Mr. Davidson refers this specimen to S. cuspidotus 

 with doubt, and says it denotes the presence of a "tubular" perforation. 

 Hence, I am very much inclined to the opinion that it rather indicates the in- 

 ternal characters of Syringothyris, than of an actual perforation through the 

 deltidium, as in Cyrtiu,* and thus seems to sustain the view that there may 

 be at least a part of the British specimens referred to S. cuspidatus, possessing 

 the internal characters of Syringothyris. This opinion receives further sup- 

 port, too, from the fact that Prof. McCoy, in describing 5. cuspidatus from 

 Irish examples, says it has an " internal, deep-seated pseudo-deltidium, with- 

 out perforation, leaving only an opening at its base." 



It is to be hoped that those who may have duplicate authentic British ex- 

 amples of Spirifer cuspidatus, may be induced to make sections across the 

 beak of the ventral valve, with the view of ascertaining whether or not any 

 of them have the internal tube of Syringothyris, and if so, to ascertain 

 whether the punctate structure is coincident with the presence of this internal 

 appendage. 



It may be proper to repeat here, for the information of those who may b 

 disposed to make such observations, that in all of these shells I have exam- 

 ined, the punctures are very small, scattering and not arranged with the regu- 

 larityseen in must types of Terebraiulidie, orin Cyrtina, Spiriferina, &c. Where 

 they happen, as is often the case, to be filled with matter of the same color 

 and translucency as the fibers composing the shell, it is exceedingly difficult 

 to see them. When very small fragments only are examined, they may like- 

 wise be readily overlooked, as the fragment may contain but one or two of 

 them, in which case they might not attract attention. Where they are filled, 

 however, with dark or opaque matter, and a fragment, say 0"03 of an inch or 

 more in diameter, is examined with a moderately low power, they are very 

 distinctly seen, and cannot be for a moment mistaken for any appearance 

 produced by a merely accidental cause. 



Note. It may not be out of place to add here, that the writer and Mr. 

 Worthenhave ascertained that the Coal-measure species, Spirifer hemiplicatus, 

 (Hall,) is a distinctly punctate shell, and that it has not the internal charac- 

 ters of Spirifer or Spiriferina, but those of Orthis, excepting that there are in 

 the ventral valve three prominent, very closely approximate, and nearly par- 

 allel laminae, extending from the beak forward to near the middle of the valve. 

 Hence we regard it as the type of a new group, probably a section of the genus 

 Orthis, for which we have in MSS. proposed the name Synjrilasma, M. & W. 



* It is nut improl able, however, that the tube in Syringothyris may have sometimes, in young 

 shell, been connected with an external opening through the deltidium, though none of the speci- 

 mens 1 have seen Bhows such au opening. 



1865.] 



