168 FISHES. CHONDROPT. Lamna. 
we call the Thresher, from the motion of its long fox-like tail, with which it 
strikes or thrashes its larger and less agHe enemy, the grampus, whenever it 
reaches the surface of the water to respire.” 
Gen. XI. LAMNA. Porbeagle. — Branchial openings in 
front of the pectorals. Snout conical. Nostrils at the 
base below. 
^15. L. cornuhica , — Teeth produced, slender, with two pro- 
cesses on each side at their base. 
Porbeagle, Borl. Corn. 265. tab. xxvi. f. 4. Penn. Brit. Zo6\. iii. 117., 
and Beaumaris Shark, ib. 118. tab. xvii., and 2d edition — Squalus cor- 
nubicus, Goodenough^ Linn. Trans, iii. 80. tab. iii. Donovan^ Brit. 
Fishes, tab. cviii. — S. Selanonus, Leach., Wern. Mem. ii. 64. tab. ii. 
f. 2 — Not uncommon. 
Length from 5 to 9 feet. Colour bluish on the back, white on the belly. 
Snout projecting. Pectorals semilunar, the first dorsal, nearly immediately 
above. Ventrals small. Posterior, dorsal, and anal fins small, opposite. 
Body contracted above and below at the setting on of the tail. Small tuber- 
cles on the lateral line. A ridge extending from the tail on each side the 
body towards the middle. Tail semilunar, the upper lobe rather largest. 
This species is said to hunt its prey in companies. Its history as a British 
fish has become much involved in error. Pennant, by adding the Beauma- 
ris shark as a new species, when, with the single exception of its apparently 
shorter snout, its claims were insufficient, and by publishing an inaccurate 
engraving from an accurate drawing by the Reverend Hugh Davis, introduced 
the confusion. Donovan advanced a step towards a reformation, by having 
examined the original drawing of Davis, and found it to correspond with the 
Porbeagle. The editor of the edition (1812) of Pennant’s British Z^oology, 
from a re-examination of the drawing of Mr Davis, asserts, that it “ corres- 
ponds exactly with the original plate;” yet, by a management which seems 
inexplicable, the engraving in the neAV edition is changed in many of its most 
important features, so as to bear evident marks of differing from the former 
plate, pronounced an accurate copy of the drawing. Dr Leach seems to have 
described from a stuffed specimen of the Porbeagle his Squalus selanonius, sup- 
posing it to be Dr Walker’s new species S. selanonius, and which he regards as 
similar to the Squalus maocimus. The Porbeagle is ovoviviparous. — It is oc- 
casionally caught in the herring-nets. 
Squalus selanoneus This species was found by the late Dr Walker, in 
Lochfyne, in Argyleshire (whence the name from Lochfyne, Sinus selanoneus 
of Ptolemy), where it appears during the herring season. Stewart, in his 
“ Elements of Nat. Hist. i. 320.,” inserts it in the section Avithout the anal 
fin, but Avith temporal orifices. In the description of this species in Dr Wal- 
ker’s MS. Adversaria for 1769, p. 155., now before me, there is no notice 
taken either of the anal fin or temporal orifices, so that I am inclined to in- 
fer the absence of both. Should this be the case, it will claim to rank as 
a new genus, occupying a place betAveen Charcharias and Lamna. I shall 
here add the descriplion as it appears in the original. “ Caput, maxilla sub- 
sequalis, superiore prominente, rostrata. Maxilla superior crassissima apice 
truncata marginata, angulo superior! obtuso suberecto. Maxilla inferior an- 
gusta. Dentes numerosi acuti. Oculi super cantham oris positi sunt. Cor- 
pus, 8-pedale oblongum, teretiusculum, cute aspera. Spiracula 5, antico 
breviore, erecta, lineari-lunata : margine postico curvato. Tria spiracula 
postica super pinnam pectoralem positi sunt, duo altera ante pinnam pectora- 
