204 THE entomologist's record. 



may make matters clear to those of our biologists who are studying 

 the subject, and may not find all these Standfussian names in our 

 chapter of " Hybridisation in Lepidoptera," Nat. Hist. Brit. Lep., v., 

 pp. 1-39. As to the mongrels noted above, Dr. Denso calls them 

 hybrids, and writes : " We do not, in Switzerland, adopt the name 

 mongrel," etc., but it is quite clear that a cross between two forms of 

 the same species is a mongrel, and of a quite different biological value 

 from that of a hybrid which is a cross between two distinct species. 



The Phryxid species were also well represented. Dr. Denso 

 exhibited 38 examples, as follows : — 



2 t? , 1 ? hjhr. eiq)horhiae s xvespertilio ? =epilohii,'Bdy. 



4 (T , 2 ? hjhi. vesj^ertilio i xeiiphorhiae 2 = dcHsoi, Musch. 



1 (J sec. hybv. epilobii s xvespertilio 5 =eugem* Moxy ) In natura 



1 i sec. hybr. eiigeni s xvespertilio ? =lippei*'Moxy \ captse. 



3 (J , 1 ? sec. hyhx. epilobii g xeiiphorhiae ? =pernoldiana, Aust. (among 



which are Austaut's two types). 

 series c? mongr. dahlii i xeiiphorhiae ? =ioetteri,\\ Turati. 



2 t? mongr. eiiphorbiae s xdahlii ? =giesekingi.\\ Turati (only examples 



known). 

 1 (? hjhr. elpeiior c? xporcellus ? =Z((c'i>ns, Dso.f (specimen unique ; taken 



wild). 

 1 s hjhr. eiiphorbiae ^ xelpenor ? = harmuthi, Kovdesch. 

 1 c? hjhr. eljjeuor 3 xeiiphorhiae 9 =pernoldi, JKCohs. 

 1 (? hjhr. g aim <? xelpenor ? =gschwandneri, Koxdesch. 



I c? hyhr. g aim j xvespertilio ? =^iZZ;/t, Gilly. 



series hyhr. gallii <? xeuphorhiae $ = phileiiphorhia, \ Mixtz. 



It would be Avell if the subscribers to Nat. Hist. Brit. Lepidoptera 

 obtained an extra copy of this list and inserted it in vol. v., p. 38, to 

 keep the catalogue there up-to-date. 



* No proof has yet been offered of the parentage of these hybrids, which 

 is largely speculative so far ; see Nat. Hist. Brit. Lep., v., p. 24. 



II Whether these are hybrids or mongrels must depend upon the specific value 

 of dahlii. Most authorities now consider dahlii to be only a local form of 

 euphorliitc, in which case these are mongrels not hybrids. 



+ Proof of parentage also wanted in this case. 



I Denso calls this galiphorbiae, but it must be referred to phileuphorhia, Miitz., 

 on the assumption of the parentage of Miitzell's example being accurate, see Nai. 

 Hist. Brit. Lep., v. pp. 24, 38. 



Billberg's Geometrid Genera. 



By LOUIS B. PKOUT, F.E.S. 

 Through the great kindness of Mrs. C. H. Fernald and Mr. J. H. 



Durrant, who (by a strange coincidence) have simultaneously sent me 

 M.S. copies of the Geometrid portion of Billberg's very rare " Enumer- 

 atio Insectorum in Museo Gust. Joh. Billberg " (Stockholm, 1820), I 

 am able at length to fill in what has been the only serious hiatus in 

 my bibliography of this family. Whatever divergent views are held 

 as to the vahdity of Billberg's work, I do not find that he added 

 anything material to Geometrid classification, and, as each of his 

 genera contained the type of an earlier genus, their names must be 

 viewed in every case as " n. nom." rather than " n. gen. " ; and as, 

 further, none of the names which he rejected were preoccupied, his 

 own are unnecessarj-. For the most part he admittedly adopted 

 Leach's 1815 scheme (Edinb. Encycl.), and rule / on Art. 30 of the 

 "International Code" of Nomenclature (see Science, October 18th, 

 1907, p. 521) seems to be applicable; but, in any case where this may 



