330 Correspondence — J. B. Scrivenor. 



pi. viii, fig. 15), must be the genotype. Two considerations have led 

 to this conclusion. 



1. Phillips mentions L. sirmosum first when enumerating species 

 which he associates with it in the genus, and before he describes his 

 Devonian form which he considers conspecific. When an author does 

 not fix on a genotype it is usual to take as such his first-named species 

 if represented by a sufiiciently well preserved specimen, which is the 

 case with this. Phillips' Devonian shell, being quite distinct, has no 

 right to the name sinuosum. 



2. The first author who clearly declares one of these species to 

 be the genotype vshould be considered to decide the matter. I have 

 shown that S. P. Woodward and P. Fischer are ambiguous. Lindstrom 

 by implication selects Z. sinuosum (Sow.) as genotype, but Professor 

 Koken is the first to do so unequivocally, for in 1889 (jN^eues Jahrb. 

 f. Miner. B.B., vi, p. 441) he states, " Der Typus ist Z. sinuosum 

 Sow. aus dem Obersilur." Again, in 1896 (Jahrb. der k.k. geolog. 

 Reichsanstalt, Bd. xlvi, Heft i, p. 1 1 7 [81]), after discussing the different 

 forms included by Phillips in the genus, he writes, " Z. sinuosa Phill. 

 ist also der Typus im wortlichen Sinne, aber nicht die ganz typische 

 Form, denn Sowerby's Terehra sinuosa aus dem Aymestrykalk mit 

 welcher Phillips sie identificirt und welche der ideale Typus der 

 Gattung ist, weicht nicht unbetrachtlich von der sinuosa des 

 Clymenienkalkes ab. Wenn man die echte, obersilurische Z. sinuosa 

 Sow. sp. neben eine Zygopleura halt sieht man am besten, ivie iveit 

 sich die letztere schon vom Ausgangspunkte der Gruppe entfernt." 



Dr. Pernor (Syst. Sil. Centre Boheme, pt. i, vol. iv, Gasteropodes, 

 tome ii, 1907, p. 324) writes after the description of the genus, 

 " Type : Loxonema sinuosum Sow." On p. 325 he divides the 

 Loxonema into two groups, and on p. 327 calls the first " Groupe de 

 Loxonema sinuosum Sow." 



M. Cossmann (p. 16) seems to think that Koken considered Terehra 

 sinuosa, Sow., a Zygopleura, but a reference to the passage quoted 

 above shows the contrary to have been the case. In the preceding 

 paragraph Koken writes, "Die letztere [Z. rugifera~], Phill. ist eine 

 carbonische Zygopleura, verwandt mit der devonischen costata Sdh., 

 aber sehr verschieden von den Loxonemen der St7iuosa-GrvL'p'pe, auf 

 welche der Name zu beschranken ist." 



Since M. Cossmann (p. 18) has substituted the name Z. Perneriiov 

 L. propinquum, Perner, which was preoccupied, and his work is prior 

 in publication to mine, the species called Z. Pernerihj me (p. 221, 

 and pi. xi, figs. 1-3) must yield to his, and I would therefore suggest 

 the name Z. Cossmanni for my species. 



J. LONGSTAFF. 

 Highlands, Putney Heath. 

 June 12, 1909. 



ARCH^AN OR LOWER PALEOZOIC ROCKS IN THE MALAY 

 PENINSULA. 



Sir, — Dr. P. D. M. Verbeek, at the end of his " Rapport sur les 

 Moluques " (edition FrauQaise du Jaarloek van het Mijnioezen in 



