320 J. W. KIRKALDT. 



2. Branchiostoma pelagicdm, Giinther. ' Challenger Reports/ vol. 



xxxi, 1889, p. 43. 



Myotomes 67. Myotome formula 36, 16 (?), 15. 



Dorsal fin low ; caudal fin paddle-shaped ; ventral fin without 

 fin-rays ; oral cirrhi wanting ; notochord projects beyond the 

 myotomes posteriorly. Nerve-cord with eye-spot ; gonads 

 in two series, twenty-six (?) on either side. 



Length 1 cm. 



Distribution. — A single specimen taken in the tow-net 

 near Honolulu. 



Remarks. — Of this species only the single specimen above 

 described is known. After Dr. Giinther^s description and 

 figure were published it was examined by Professor Lankester 

 by means of transverse sections, but the state of preservation 

 was such as to render any satisfactory observations impossible. 

 The specimen had been stained strongly in carmine before 

 it came into Dr. Giinther's hands, and mounted under a 

 cover-glass which had greatly compressed it. 



Tabular Enumeration of the Genera and Species of 

 Branchiostomid^e. 



Genus I. — Branchiostoma, Costa. 



Sub- genus Amphioxus. 



1. A. lanceolatus, Yarrell (Pallas). 



2. A. californiensis, Cooper. 



3. A. caribseus, Sundevall. 



4. A. Belcheri, Gray. 



Sub-genus Heteropleuron. 



1. H. Bassanum Giinther. 



2. H. cingalense, J. W. Kirkaldy. 



3. H. cultellum, Peters. 



Genus TI. — Asymmetron, Andrews. 

 1. A. Lucayanum, Andrews. 



