Occasional Papers of the Alitscum of Zoology 5 



Most morphological writers have retained the name Amphi- 

 oxus either for all lancelets or for the typical genus, despite 

 the universally accepted fact that Amphioxus is a strict homo- 

 nym of Branchiostoma. Similarly, among those who have 

 accepted the name Branchiostoma in the generic sense, some 

 have persisted in using the name Amphioxus for the typical 

 subgenus of Branchiostoma, in violation of a nomenclatural 

 practice which is thus prescribed by the International Code: 

 "If a genus is divided into subgenera, the name of the typical 

 subgenus must be the same as the name of the genus." The 

 present writer is of the opinion that the name Amphioxus 

 should be adopted for the typical lancelets, and would welcome 

 a decision of the International Commission which would ren- 

 der this name available. 



Diagnosis of the Atlantic and eastern Pacific species are 

 given below, as well as notes on all the species. 



4. Branchiostojiia lanccola,tum Pallas 



Limax lanceolatits Pallas (1776). 



Branchiostoma lubricuin Costa (1834, 1843). 



Amphioxus lanceolatus Yarrell (1836) ; Lankaster (1889) ; Kirkaldy 

 (1895) ; Lonnberg (1904), and most other authors. 



Branchiostoma lanccolatum Gray (1851) ; Andrews (1893) ; Smitt 

 (1895), etc. 



{!) Branchiostoma lanceolatiiin Tattersall (1903). 



All references to lancelets under the names just listed, from 

 localities other than Europe, with the doubtful exception of 

 that of Tattersall, obviously refer to other species. 



Diagnosis: — For comparison with the diagnoses of the sev- 

 eral Atlantic American species of Branchiostoma here distin- 

 guished, a brief characterization of the European lancelet is 

 made. Ray-chambers (in material from Naples) in moderate 

 numbers in the dorsal fin (224 to 256 in nine specimens ; aver- 

 age 236), but in high numbers in the preanal fin (35 to 47 in 



