EEPORT ON THE BRACHIOPODA. 35 



elongated, and the strise nearly twice as numerous, being about thirty to forty in the 

 European, and fifty to sixty in the American specimens. No account of the internal 

 bony process is given in any description except that by Mr Couthouy. These would 

 afford the best possible specific character were it not that they are usually more or less 

 broken. But I have been relieved from all further speculation by the receipt of specimens 

 from Dr Loven which settle the identity of our species with the European caput- 

 serpentis." Mr W. H. Binney seems to be of a different opinion, for he adds, after 

 Gould's observations above recorded : " I have retained the above remarks from the 

 former edition, because our shell is so generally still regarded as identical with the Euro- 

 pean species, but further examination of numerous specimens has led me to coincide with 

 Dr Stimpson, who has di'edged extensively both in British and American seas, and in his 

 opinion, the species differs from European Ter. caput-serpentis sufficiently both in shell 

 and animal." 



G. B. Sowerby in p. 344 (1846) of his Thesaurus Conchyliorum observes that 

 Ter. septentrionalis is distinguished from Ter. caput-serpentis by its much finer 

 radiating strise, its larger and less oblique foramen, and by its rather more extended and 

 somewhat differently formed internal appendages. Mr Lovell Reeve in his Monograph of 

 Terebratula, Conch. Icon., 1861, places Ter. septentrionalis as a synonym of Ter. cainit- 

 serp>entis, stating that, " Ter. caput-serpentis ranges throughout the European seas from 

 the Arctic to the Mediterranean, mostly at considerable depths, and it appears abundantly 

 in a more finely-striated state in the northern seas of the United States. The North 

 American form is given as a distinct species in the Museum Catalogue with Couthouy 's 

 name Ter. septentrionalis, but is untenable, as Dr Gould himself admits in his Eeport on 

 the Invertebrata of Massachusetts. Dr Gwyn Jeffreys, in his valuable British Conehology, 

 considers Ter. septentrionalis as a local variety of Ter. cap>ut-serpentis, and adds that it 

 has a thinner shell, finer ribs, and a white colour, and that he has compared more than a 

 hundred specimens of both forms. Mr Dall in his Revision of Recent Species of 

 Brachiopoda, in the Proc. Phil. Acad. Nat. Sciences for July 1873, considers Ter. caput- 

 serpentis and Ter. septentrionalis as distinct species, but in a letter to me, dated November 

 1877, he adds : " I consider Ter. septentrionalis as merely a geograj)hical race of Ter. caput- 

 serpentis, but I think Ter. iinguiciilus is distinct. The difference between the last and the 

 Atlantic form is chiefly in the loop which remains in Ter. unguiculus long open, and is 

 much larger and broader proportionately to the shell than in Ter. caput-serpentis." I have 

 likewise, thanks to the Challenger Expedition dredgings and to Professor Verril, been 

 enabled to compare a very large number of specimens at all ages of the species and its 

 variety, and quite concur with the prevailing opinion that there exists very little differ- 

 ence between the two, but still I think sufficient to warrant us in retaining the varietal 

 designation of septentrionalis. In addition to the generally finer striation, the shell is 

 more regularly oval and rounded in front than in the Ter. caput-serpentis, although 



