294 PLAGIOSTOMATA. 



Genus III — Ztg^na, Guvier. 



Oestracion, Klein: CesfrorMmns, Blainv. : Sphyrna (Rafin.) Miill. and Henle : 

 Eusphyra and Reniceps, Gill. 



The anterior portion of the head broad, flattened, and laterally elongated with the 

 eyes aituated at its lateral extremities and the nostrils at its fore border. A membrana 

 nictitans present. Spiracles absent. Mouth crescentic. Teeth similar in both jaws, 

 placed obliquely and notched. The first dorsal fin spineless, situated above the 

 interspace between the insertions of the pectoral and the ventral : caudal with one 

 notch, and a pit at the commencement of the fin. 



1. ZygSBna malleus, Plate CLIV. 



Libella, Belon. p. 61 ; Salvian. p. 128, t. xl ; Aldrov. p. 408 ; Jonston, t. vii, 

 p. 8 ; Zygcena, Willngliby, lib. iii, c. vii, p. 55, pi. Bl ; Rondel, p. 389 ; Gesner. 

 p. 1050 ; Ray, Synop. Pise. p. 20. Squalus, sp. Artedi, Genera, p. 44, no. 7, and 

 Synon. p. 96, no. 7 ; Gronov. Mns. Ich. i, pp. 63, 139, and Zooph. p. 146. 

 Zygene, Dnhamel, Peches, ii, Sect, ix, pi. xxi, f . 3-8. Oestracion, sp. no. 1, Klein, 

 Pise. Miss, iii, p. 13. Gorunda, Parra, Lam. 32. Kama sorra, Russell, Fish. 

 Vizag, pi. xii. 



Squalus zygxna, Linn. Syst. Nat. p. 399; Bl. t. cxvii; Bonnaterre, Ency. 

 Ich. p. 9, pi. vi, f. 15 ; Bl. Schn. p. 131 ; Lacep. i, p. 267, pi. viii, f . 3 ; Gmel. 

 Linn. p. 1494 ; Briin. Pise. Mass. p. 4 ; Risso, Ich. Nice, p. 34 ; Mitchell, Trans. 

 Lit. and Phil. Soc. New York, i, p. 284 ; Gronov. ed Gray, p. 6. 



Zygwna malleus, Shaw, Nat. Misc. pi. cclxvii ; Val. Mem. Mus. ix, 1832, p. 223, 

 pi. ii, f . 1 ; Risso, Eur. Merid. iii, p. 126 ; Paget, Natural History of Yarmouth, p. 17 : 

 Jenyns, Manual, p. 607 ; Yarrell, Brit. Pish. (ed. 1) ii, p. 405, c. fig. (ed. 2) ii 

 p. 604 (ed. 3) ii, p. 486 ; De Kay, New York Fauna, Fish. p. 362, pi. Ixii, f. 204 

 Storer, Proc. Bost. Soc. Nat. Hist, i, p. 36 ; Gijnther, Catal. viii, p. 381 ; Klunz 

 Fiseh. Roth. Meer, 1871, p. 666 ; Day, Pish. India, p. 719, pi. clxxxvi, fig. 4 

 Giglioli, Catal. Pesc. Ital. p. 61 ; Moreau, Poiss. France, i, p. 324, fig. 48, 49. 



Zygcena leweni, Griffith in Cuv. An. King, x, p. 460, pi. i. 



Sq^ialus -malleus, Risso, Ich. Nice, p. 34. 



Sphyrna zygcena, Bonap. Faun. Ital. Pese. iii, t. f. 1 ; Miill. and Henle, p. 51 ; 

 Gray, Cart. Fish. p. 48; White, Catal. p. 126; Canestrini, Fauna d'ltalia, Pesc. 

 p. 47. 



Cestracion zygcena, Gill, Ann. Lye. Nat. Hist. New York, vii, p. 403 ; Dumeril, 

 leh. i, p. 382 ; and Oestracion lleuwenii, Dumeril, p. 383. 



Hammer-head, Couch, Fish. Brit. Isles, i, p. 70, pi. xvi. 



Head hammer-shaped and about three times as wide as it is long. The hind 

 edge of the laterally expanded head, nearly or quite equals its width near the eyes. 

 A groove exists along almost the entire extent of its anterior edge. Nostrils close 

 to the eyes. Teeth — oblique, externally notched, otherwise smooth in their entire 

 extent. Fins — the dorsal arises on a line slightly behind the base of the pectoral, 

 and extends two-thirds of the distance to above the ventral ; second dorsal inserted 

 above the last third of the anal than which it is much smaller. Golours — body and 

 fins slatey-gray ; under surface of a dull white. 



Names. — It has been termed the zygcena, or balance fish. Le Marteau, French. 



Habits. — Fierce, and large ones generally inhabit deep water. 



Breeding. — The yelk-bag is connected to the walls of the uterus (Grey). 

 There were thii-ty-one young ready for exclusion inside the Welsh specimen. 



Habitat. — Cosmopolitan. One five feet long was found dead off BanfEshire 

 in 1861 (Edward) ; in October, 1829, one was taken at Yarmouth, the head and 

 tail of which were presented to the Norwich Museum. In 1834 another at 

 Newlyn, in Cornwall. July 31st, 1865, one, 13 ft. 7 in. long, was perceived 

 floundering among the rocks at Ilfracombe ; it was secured by ropes and towed 

 inland. The eyes were nearly covered by crustacean parasites : two thornbacks 

 and a bass were found inside it, together with numerous large intestinal worms. 

 1839 one, 10 ft. 3 in. long, taken in August in Carmarthen Bay (Dillwyn). 



