484 PROCEEDINGS OF THE ACADEMY OF 



laborers on that group. Happily those families whose arrangement most re- 

 quires modification are represented by species found along the coasts of Cali- 

 fornia. I therefore, submit through the medium of a classification of those 

 species, some of the changes which appear to be necessitated in the present state 

 of our knowledge. 



Order SQUALI (llutter et Henle) Agassiz. 

 Suborder SQUALI Gill. 

 Squalidae veri Bonaparte, Selachorum Tabula Analytica, p. 4,U838. 



Pectoral fins produced directly outwards, or curved backwards from the an- 

 terior basal angle. 



Caudal fin heterocercal and with a more or less developed inferior lobe pro- 

 current forwards beneath the vertebral column. 



Family GALEORHINOIDJE Gill. 



Les Squales sp. Cuvier, Regne Animal, tome ii. p. 123, &c, 1817. 



gqualidse, ( (10) Squalini, (19) Truenodontini) Bonaparte, Selachorum Tabula 



Analytica, p. 5. 

 Carcharis part. 

 Trisenodontes 



Galei \ Mailer and Henle, Systematiscbe Bescbreibung der Plagi- 



Scylliodontes ostomen, pp. 28, 5557, 63, 64. 



Musteli J 



Nictitantes Owen, Lectures on Comparative Anatomy, vol. ii. p. 51, 1846. 



C archaridae ) Richardson, Encyclopaedia Britannic*, vol. xii. (Ichthyology) p. 



Galeid?? J 323. 



Carchariodei ( Bleeker, Enumeratio Specierum Piscium hucusque in Archipelago 



Galeoidei \ Indico Observatorum, &c. 7 pp. 11, 12. 



Galeorhinoidaa Gill, Analytical Synopsis of the Order of Squali, pp. 29, 30, 33. 



Body elongated, su&cylindrical, gradually tapering towards the caudal fin. 



Scales miaute, more or less rhomboid and imbricated, and generally sur- 

 mounted by longitudinal keels. 



Head more or less depressed and plane, oblong, semi- elliptical or conic above, 

 with the snout projecting on the plane of the head, wit& it3 margin thin, more 

 r less rounded, and declining obliquely backwards to the mouth. 



Eyes lateral, submedian or anterior, with the nictitating membrane dis- 

 tinct. 



Mouth inferior, large and arched in front. 



Teeth compressed, with trenchant and entire or seirated edges ( Ga!eorhininm,y 

 or small and paved. 



Nostrils inferior, and near the sides of the snout ; simple and generally 

 with a triangular flap from the anterior or inner border. 



Spiracles, obsolete or developed. 



Branchial apertures five, the last of which are small, and above the base of 

 the pectoral fin. 



Dorsal fins two ; each is curved towards the anterior angle wbicb is rounded 

 and more or less projecting, especially that of the first fin, while the posterior 

 angle is acutely produced backwards. First dorsal large and situated more 

 or less in advance of the ventral fins , second moderate or small, and above or 

 nearly above the anal fin. 



Anal fin generally similar to tbe second dorsal in form and size, rounded at 

 its anterior angle, and acutely produced behind. 



Caudal fin decidedly heterocercal ; the upper or vertebral lobe moderately 

 elongated and abruptly curved upwards and backwards, and with the mem- 



[Oct. 



