riscLs. 31 



Two specimens were collected at Tort Mulle. Their dimensions 



are : — 



Total length 27 lines. 



Length of tail 11^ „ 



Length of head 5 „ 



Length of snout 2^ „ 



BKANCHIOSTOMA. 



The recent discovery of a second undoubtedly distinct species of 

 Leptocardian on the coast of Australia (Epigonichihys cultellus) 

 as well as the acquisition of several well-preserved examples, for 

 which we are indebted to Dr. Coppinger, induced me to reexamine 

 all the specimens in the British Museum, which, having been pre- 

 served in spirit for a great many years, were by themselves not 

 reliable evidence as to the question whether the European Lancelet 

 is a cosmopolitan form, or represented by several distinct species in 

 other parts of the globe. 



J. Midler (' Leber d. Bau d. Braiichioxtoiiia," p. 84) was unable to 

 observe any differences between Brazilian and European specimens ; 

 and I not only took the same view, but considered specimens from 

 Indian and Australian localities to be referable to one species only. 



I have now convinced myself that this view (Cat. Eish. viii. 

 p. 513) is incorrect, and that Sundevall was quite right in drawing 

 attention to the number of myocommas as an excellent taxonomic 

 character. This number can be ascertained even in specimens in 

 an indifferent state of preservation, and varies very little ; whilst 

 the extent in depth and length of the delicate fin which surrounds 

 the posterior part of the tail is a much less reliable character, subject 

 to much alteration by the spirit, if great care is not taken in the 

 preservation of the specimens. 



The species of Branchiostoma would then be the following : — 



1. Branchiostoma elongaturn, 



Sundevall, CEfvers. Vet.-Akad. Forhandl. 1852, p. 147; and 1853, 

 p. 12. 



Myocommas 49 + 18 + 12 = 79. 

 Coast of Peru. 

 Of this species I have not seen specimens. 



2. Branchiostoma bassanum. 



Myocommas 44 + 13 + 18=75, or 

 43 + 15 + 17=75, or 

 45 + 14 + 17=76. 



Body lower than in B. laaceolatum : dorsal and anal fins low, 

 with the caudal portion slightly wider ; vent lateral ; (oral cirrhi 

 10 + 11). 



These are the specimens from Bass-Straits which I formerly 

 referred to B. lanceolatum. 



