THE FISHES OF THE IRISH SEA. 63 



the Dee and from the Mersey, and White from Bangor. We have it also from Barrow 

 Channel ; it has been occasionally caught in the Ribble, and it has been taken, rarely, around 

 the Isle of Man. 



Division II. ELASMOBRANCHII. 



With five to seven pairs of branchial arches bounding and separating the gill clefts, 

 which are converted into gill-bearing pouches by septa continuous with the outer skin ; there 

 is no opercular fold. The intestine has a spiral valve, and ends in a cloaca. Without mem- 

 brane or cartilage bones ; skin with numerous small enamelled denticles ; skeleton mainly 

 cartilaginous. Males provided with a pair of claspers. Ova few and large. 



Order I.* SELACHII. 



Mouth transverse and ventral ; head with a snout or rostrum. Heart with a conus 

 arteriosus. The paired fins are not archipterygial. The caudal fin is heterocercal. 



Sub-order I. ASTEROSPONDYLI. 



(Sharks and Dog-fishes.) 



If the centra of the vertebrae are calcified it is in a radiating or stellate form. Spiracles 

 absent or reduced. Anal fin present. Pectoral fins separated from the head. 



Family CARCHARIID/E. 



CARCHARIAS GLAUCUS (Linn.) Blue Shark. 



(Day's British Fishes, vol. II., p. 289, PI. CLII.) 



This shark is widely distributed in the Atlantic and Pacific Oceans, and is frequently 

 found in our seas during the warmer parts of the year. We also have records of their capture 

 round the Isle of Man and off the Welsh coasts. They are common off the "Smalls," 

 attending the schools of herring. A specimen in the Liverpool Free Public Museum, taken off 

 the Orme's Head in September, 1882, measured 5 feet 10 inches in length. 



GALEUS VULGARIS (Linn.) Tope. 

 (Day's British Fishes, vol. II., p. 292, PI. CLIII.) 



(Fish. Mus., Zool. Dep., Univ. Coll., Liverpool.) Local name, "Dog-fish." 

 This fish has a very wide range throughout the oceans of the world. It is abundant in 

 our seas, especially in summer. It has been frequently taken off Anglesey, and the coast of 

 North Wales, since Pennant recorded it from Flintshire. It is sometimes taken on lines set 

 for cod. One was caught at Piel, in Barrow Channel, in August, 1900. We have also seen it 

 taken in the Horse Channel at the mouth of the Mersey, at the Bar, and above Liverpool in the 

 estuary. There was a line fishery for this fish at one time off Formby, which was followed by 

 the Southport fishermen. They are still sold in Darwen and Blackburn, in Lancashire, for 

 food, and are known locally as " Darwen salmon." 



* Extinct forms, such as the Ichthyotomi, and groups wholly unrepresented in our seas, such as the 

 Holocephali, are omitted from this classification. 



