Occasional Papers of the Museum of Zoology 13 



form can be distinguished only by its diagnostic myotome 

 formula : 



Branch'wstoma faftcrsalll, — 40-(-2o-|-i2. 



Branchiostouia calif ornicnse, — 43 to 48-(-i6 to 19+8 to 10. 



Branchiostorna capensc, — 46 to 48-{-iS to 19+9 or 10. 



13. Branchiosioma capense Gilchrist 

 Branchiostorna capense Gilchrist (1902) ; Herdman (1904). 



14. Branchiostorna clongatmn Sundevall 

 Amphlo.vus elongatus Sundevall (1852) ; Kirkaldy (1895). 

 Branchiostorna elongatum Sundevall (1853) ; Andrews (1893) ; 

 Willey (1894) ; Steindachner (1898) ; Herdman (1904) ; Lonnberg 

 (1905) ; Snodgrass and Heller (1905) ; Goldschmidt (1905) ; Porter 

 (1909) ; Regan (1913)- 



This species is a true Branchiostoma, not a Heteropleuron, 

 as Lonnberg has provisionally suggested. The material 

 recorded by Snodgrass and Heller from the Galapagos Islands, 

 and by Porter from Valparaiso Bay, Chile, has been 

 re-examined. 



Diagnosis (based solely on two mature specimens from 

 Valparaiso Bay) : — Dorsal ray-chambers numerous, but not 

 accurately countable, and moderately high ; preanal chambers 

 about 65 to 75, much more numerous than in other species of 

 Branchiostoma. Anus located slightly in advance of middle of 

 lower caudal lobe; distance from atriopore to origin of this 

 fin lobe contained 1.3 times in total distance behind this point. 

 Preatrioporal length, 2.4 to 2.6 times the postatrioporal length. 

 Myotomes very oblique; the formula, 48 to ST-\-i8-\-i2 or 13= 

 79 to 81. Gonad pouches 37 (counted on only one side of one 

 specimen). Oral hood reduced in size, as in B. calif orniense. 

 Length, 6.25 to 6.85 cm. 



Genus 3. Dolichorhamphus Willey 



Dolichorhamphus Willey (1901). 



Genotype. — DolicJiorliauiphits indicus Willey. 



This genus appears to the writer worthy of recognition, as 

 distinct from Branchiostoma. 



