part 2] ACLivixA and aclisoides. 61 



noted that the variet}^ ex'ujua of Aclisina pulclira De Koninck and 

 A. eloiKjata (Fleming) have the most extended range, the former 

 making its appearance in the Calciferous Sandstone Series, and 

 continuing throughout the Lower Limestone Series and the Upper 

 Limestone Series into the Millstone Grit. In Belgium the species 

 is only recorded from Tournai, where specimens attain a greater 

 size than any Scottish variety that I have seen. A. elongata has 

 a similar range in Scotland, except that it has not been i-ecorded 

 from the Millstone Grrit. It also occurs in the Yoredale Series 

 of England, and is probably represented in Ireland and Belgimn. 

 L. Gr. de Koninck figures a small gasteroj^od from A^ise on pi. xxxiii, 

 iigs. 1-5 & 46, in ' Faune du Calcaire Carbonifere de Belgique ' 

 pt. iv, Ann. Mus. Koy. Hist. Nat. Belg. vol. viii (1883), which 

 greatly resembles this species ; but it is undescribed. as it was 

 lost. 



Eight species occur in both the Lower and the Upper Limestone 

 Series: namely,^, costatula, A. attenuata, A. aciculata, A. tenui- 

 striata, A. q^uadrata, A. similis, A. sfrlatissima, and A. / multi- 

 volva. Of these, A. similis and probably A. striatissima are 

 found also in Belgium. 



Five species are confined to the Lower Limestone Series : namely, 

 A. pusilla, A. parvula, A. terehra, A. elegant id a, and A. venusta. 



Four are limited to the Upper Limestone Series : nameh^, 

 A. delicatulct, A. fahe)\ A. iiiicula, and A. siihelonrjata. 



A. fj rant one as is has onh^ been found in the Calciferous Sandstone 

 Series. 



Of the two species referred to Aclisoides, A. striatula has the 

 widest range, occurring in both the Lower and the Upper Lime- 

 stone Series of Scotland, as ^vell as in England, the Isle of Man, 

 and Belgium; while A. I armstrongiana is onl}^ known from the 

 Lower Limestone Series of Scotland. This subgenus is confined 

 to the Carboniferous Period. 



In addition to the fourteen foreign Carboniferous species of 

 Aclisina previously mentioned, three have been described by 

 Miss Clara Gr. Mark,^ and three others have been doubtfully re- 

 ferred to the genus by her ; these latter, however, do not appear 

 to possess the characteristic lines of growth. The thi-ee former 

 are A.forniosa, A. conditi, and A. piimila, from the Portersville 

 Limestone, Conemaugh Formation. 



Besides these, a new species from the Zechstein, A. heneventa,'^ 

 has been described by E. Dietz, and also one from the Devonian, 

 A.fiigitiva Barrande, by Dr. Jaroslav Perner.^ 



This genus has been stated to range from the Devonian to the 

 Permian : if, however, the species A. obscura Donald,* doubtfully 



1 Geol. Siirv. Ohio, ser. 4, Bull. 17 (1912) p. 314 & pi. xvi, figs. 7-10. 



2 Jahrb. K. Preuss. Geol. Landesanst. vol. xxx, pt. i (1911) p. 475 <& 

 pi. XV, fig. 1. 



^ ' Systeme Siliirien du Centre de la Boheme, vol. iv : Gasteropodes ' vol. ii 

 (1907) p. 372 & pi. ex. figs. 19-20. 



" Q. J. G. S. vol. Iviii (1902) p. 337 & pi. ix, fig. 12. 



fi2 



