248 PLAGIOSTOMI. 



Mr. Templeton noted this species as taken " occasionally." The spe- 

 cies has not come under my notice in the N., nor can Dr. Ball attest to 

 its being seen by him on the Irish coast, but some ova sent to the Belfast 

 Museum, in Dec, 1843, seemed to me to belong to this sp., and the fol- 

 lowing paper drawn up on them was published by me in the Annals Nat. 

 Hist, in 1844 :— 



" On Ova believed to be those of the Larc/e-spotted Dog-fish, Scyllium 

 Catulus, Linn. (Sp.) 



" About tlie middle of December last there were sent to the Belfast Museum 

 two plants of the tangle {Laminaria dir/itata), dredged together ofi" Killiiichy, 

 Strangford Lough, from a depth of between two and tlu'ee fathoms, and having 

 many hirge and remarkable ova attached to them by tendrils, like those on the 

 well-known ' jjurses,' as they are called, of "tlie common dog-fish [Scyllium Ca- 

 niciila), though they evidently belonged to a different species. Tliey were new to 

 me and interesting in several respects. To the one plant of tangle were attached 

 fourteen, to the other twelve, of these ova ; of the fourteen, six were very old, six 

 of middle age,' and two quite fresh — of the twelve attached to the other plant, four 

 were very old, four of middle age, and four quite fresh. Those called fresh had 

 the ' white and yolk," as in a newly-laid hen's egg ; from those termed of middle 

 .age the young tisli had probably long since escaped ; none remained to bear 

 testimony to its species. The age of the different ova was denoted, not only by 

 their own appearance, but by that of the moUusca, zoophytes, &c., parasitical upon 

 them; — on the oldest were Anomia an inch in diameter; Discopoi'a hispida, 

 Tubularia ramosa, Celhtlaria repfans, all full-grown ; and on them, and those 

 of middle age, were Lepralice (Johnston) of various species, Nullipora;, and 

 masses of the ova of Buccinum undatum. 



" The number of ova of different ages suggested certain points of inquiry. Their 

 deposition at three different periods of time on the same plant led to the sug- 

 gestion that the fish may, like certain birds, as the different species of Hirmi- 

 dines, for example, return time after time to the same spot to deposit its eggs. 

 We can indeed only infer that the same individual has deposited ova on the dif- 

 ferent occasions, but the probability is in favour of such inference. That the 

 salmon (Scilmo Salar) returns to its native river — if not to the same 'bed ' — to 

 spawn, we have a notable example in the North of Ireland, where, from the cir- 

 cumstance of the fish of the adjacent rivers Bann and Bush being distinguished 

 from each other by certain peculiarities, those of every age from each river in 

 returning to the fresh water from the sea are known always to seek the ascent 

 of their native stream. 



" Being unable to find any ova described like those imder consideration, I 

 made a sketch of one and submitted it to my friend Mr. Yarrell for his opmion, 

 together with several queries, remarking at the same time, that as ' the ova are 

 evidently generically related to those of .S". Canicnla, the first impression is, that 

 they are those of the most nearly allied species, Sci/llitim Catidas, especially as 

 w^e find those of the next nearest ally, at least among British species — Sqiialus 

 anntdafus, Nils. {Pristiurus melanostomus, Bonap.) — to be of a diff'erent form; 

 but that, if they belong to ^\ Catulus, which is said not much to exceed .S. Ca- 

 nicida in size, it will be singidar that the ova should so greatly exceed those be- 

 longing to that species as to be double their size, and, in consequence of their 

 much greater strength, about four times their weight. The transverse markings 

 represented in the drawing denote plaits, which give to the exterior a handsome 

 appearance ; but they are not of specific value, the surface of some ova being 

 quite smooth, of others partially or wholly plaited.' It was added — ' Is it known 

 how often the Sci/llia deposit their ova ? how many are deposited at one time ? 

 how long after deposition the young fish bursts its prison ? ' In the event of 

 Mr. Yarrell's not knowing the ovum (which proved to be new to him likewise), 

 he was requested to send the drawing, &c., for Mr. Couch's opinion. With re- 

 spect to S. Canicula Mr. Yarrell remarked, — 



" I never remember to have observed more than one egg in each oviduct ready 



