210 MRS. JANE LONGSTAFF ON Play 1909,. 



14. 0^ tfzc Genus Loxonema, with Descriptions ofN'nw Proierozoic 

 Species. By J awe Longsiaff (nee Donald), F.L.S. (Com- 

 municated by Dr. G. B. Longsiaff, M.A., F.G.S. Bead 

 January 13th, 1909.) 



[Plates X & XI.] 



There is considerable confusion with regard to the genotype of 

 Loxonema, Phillips. This has arisen because Phillips did not fix a 

 genotype himself, and because he confounded a Devonian form with 

 his first-mentioned species. This last is the Silurian Terebra (?) 

 sinuosa of Sowerby. 1 Both the Devonian form which Phillips calls 

 Loxonema sinuosum and Sowerby's holotype bear the characteristics 

 of the genus as defined by him, but they certainly are specifically 

 distinct. The genus was founded by Phillips in 1841; 2 and, though 

 I bave given the original diagnosis in a former paper, it seems 

 advisable to reproduce it here : — 



' Spiral, turriculated ; whorls convex, their upper edges adpressed against the 

 next above ; without spiral band ; mouth oblong, attenuated above, effused 

 below, with a sigmoidal edge to the right lip ; no umbilicus (?) ; surface covered 

 by longitudinal threads or ridges, generally arched. 



' These observations are merely provisional until the form of the aperture is 

 more perfectly known. The shells have been placed as Melanin, Bissoa, Terebra, 

 Turrit ella, and Scalar ia. 



' In regard to the number of species mentioned, I must observe that I find it 

 impossible to do otherwise than preserve the names of all as distinct varieties ; 

 but that it is very probable most of them are only varieties of three or four 

 types, one having L. sinuosa for one extremity and L. Hennahii for the other ; 

 a second related to L. ticmida and L. lincta ; a third to L. rugifera. Count 

 Miinster's figures referred to are certainly of Devonian species.' (Op. cit. 

 pp. 98-99.) 



A. d'Orbigny appears to have been the first to notice the error in 

 identification/ for he enters the Silurian form as 



' sinuosa, d'Orb., 1847. Terebra sinuosa, Sow., 1839 in Murch. Silur. Syst., 

 pi. 8, fig. 15. Angleterre, Ludlow-Eock ' 



and the Devonian one as 



' Phillipsii, d'Orb., 1847. L. sinuosa, PhilL, 1841. Pal. Foss., pi. 38, fig. 182 ; 



Tereb. id. (non sinuosa), Sow. Sil. Syst. pi. 8, fig. 15. Angleterre, Petherwin,' 



but does not make any remarks. 



H'Coy 5 evidently considers the Devonian distinct from the 

 Silurian form : for, when describing L. nexilis, Sow. he writes thus : 



' I should think the S. Petherwin shell figured and described by Phillips, 

 Pal. Foss., as the Silurian Terebra sinuosa of Sowerby, belongs to the present 

 species.' 



They are not, however, conspecific (see pp. 212 & 217). 



Lindstrom points out, in his synonymy of L. sinuosum, Sow., 6 



i < Silurian System ' 1839, p. 619 & pi. viii, fig. 15. 



2 ' Pal. Foss. of Cornwall, Devon, &c.' p. 98. 



3 Quart. Journ. Geol. Soc. vol. lx (1905) p. 564. 



4 ' Prodrome de Paleont. Strat.' vol. i (1850) pp. 29 & 62. 



5 'Brit. Pal. Foss.' 1855, p. 399. 



6 ' Silur. G-astr. & Pter. Gotland ' Kongl. Svensk. Vetensk.-Akad. Handl. 

 n. s. vol. xix (1884) no. 6, p. 142. 



