250 
PLAGIOSTOMI. 
“ Length of recent ovum, of Scyllium Catulus ? 4 inches 6 lines ; breadth 1 
inch 9 lines ; depth 3 — 4 lines ; surface smooth or plaited transversely ; sides 
very strong and closely plaited throughout ; tendrils very strong. Colour a 
uniform brown, but differing in shade in different ova. 
“ Belfast, May, 1844.” 
The Blaok-mouthed Dog-fish, Pristiurus melanostomus, Bonap., 
Scyllium, melanostomum , Bon., 
Has been obtained on the northern coast. 
We are indebted to the Ord. Survey for this addition to our Fauna, 
two individuals having been obtained by the collectors at Portrush, near 
the Giant’s Causeway. Captain Portlock, in contributing a notice of this 
shark, observed that “ in the work of Muller and Henle, the genus Pris- 
tiurus, Bonap., is described as having a row of small prickles on the tail- 
fin, and Scyllium Artedi is figured and described by itisso as having but 
a single row. — In Yarrell’s description of Scyll. melanostomum two rows 
are mentioned, and in our specimens they certainly exist, — ought not, 
therefore, the single row to be dropped as a generic character, and 
Risso’s termination of his specific characters used, viz. ‘ pinna dorsi ex- 
tremitate [supra] spinosa ? ’ may not the one and two-rowed individuals 
be of distinct species, and the black mouth be common to both ? ” Mr. 
Yarrell, in his second ed. of Br. Fishes, vol. ii. p. 497, says, “ it has also 
been taken in the North of Ireland by Captain Portlock, to whom I am 
indebted for sketches, from which the different subjects forming the 
vignette at the end were taken.” 
The Fox-shark, or Thresher, Carcharias Vulpes, Cuv., 
Can be announced only on circumstantial evidence as frequenting the 
Irish coast. 
M‘Skimmin, in his History of Carrickfergus (3rd edit. p. 358), notices 
the 
“ Squalus Vulpes , Sea-Fox Thresher ; sometimes seen off the Copeland Islands, 
and heard after night making a noise with its tail against the water.” 
Templeton includes the species in his Catalogue, remarking merely 
that it is “ rare on the coast, but occasionally seen about the Copeland 
Islands.” 
Major Walker, of The Lodge, County Wexford, noticed this species in 
a letter written to me in July, 1846, from the statement of fishermen who 
had seen a large fish beating a grampus or small whale in the Sound, be- 
tween the two Saltee Islands, and who reported that every blow “ sounded 
like the distant report of a cannon.” This description will apply only to 
the species under consideration, which owes its name of Thresher to the 
propensity here mentioned. 
“ Mr. Couch says it is not uncommon for a thresher to approach a herd 
of dolphins (Delphini) that may be sporting in unsuspicious security, and, 
by one splash of its tail on the water, put them all to flight like so many 
hares before a hound.” — Yarrell’s Brit. Fish., vol. ii. p. 523. 
The Blue Shark, Carcharias glaucus, Cuv., 
Is taken on the coast, chiefly southwards. 
Dr. Ball informs me that this species is occasionally captured at the 
Nymph Bank, and also at Youghal. I examined the jaw of one from the 
former locality, in that gentleman’s collection : the fish to which it be- 
