CLASSIFICATION OF THE CEPHALOCHOKDA. 275 



BranciiiostomidyE, divided into five genera — 



(1) Branchiostoma — -bilateral gonads, rayed ventral 



fin, low dorsal fin, and expanded candal membrane. 

 B. lanceolatum, B. belcher i, B. caribbceum, B. 

 calif omiense, B. elongatum. 



(2) Paramphioxus 1 — unilateral gonads, rayed ventral 



fin, low dorsal fin, expanded caudal membrane. 

 P. bassanum. 



(3) Epigonichthys — unilateral gonads, reduced ventral 



fin, bigb dorsal fin and expanded caudal membrane. 

 E. cultellus. 



(4) Asymmetron — unilateral gonads, no ventral fin, low 



dorsal fin and extended attenuated tail. A. 

 lucayanum. 



(5) Amphioxides (a new generic name which he pro- 



poses for B. pelagicum) — bilateral (?) gonads, no 

 ventral fin ( ? J, low dorsal fin, expanded caudal 

 membrane, no oral cirri. A. pelagicum. 

 In 1897 Willey 2 described a new species of the genus 

 Asymmetron under the name A. caudatum the myotome 

 formula of which was 40 (44) 9, 11 ; and in 1901 3 he 

 described a further species Dolichorhynchus indicus whic n 

 he placed in a new sub-genus of Branchiostoma, founded 

 on the fact that the preoral lobe of this new species was 

 very well developed. At the end of his paper he added 

 an outlined classification of the group, which differed 

 somewhat from that of Kirkaldy. The full classification 

 was as follows : — 

 Branchiostomid^e — 



Genus I. Branchiostoma. 



Sub-genus I. Amphioxus, e.g., A. lanceolatus. 

 Sub-genus II. Dolichorhynchus, e.g., D. indicus. 



1 Par amphioxus is a generic name proposed in 1893 by Haeckel for 



B. bassanum. 



a Q.J.M.S. Vol. xxxix. *Ibid. Vol. xliv. 



