1054 



SCANDINAVIAN IMSIIK.S. 



tliat of a respiratury or^an. It is ;i relic of the seg- Acijieiii^rr. The foriiier, of wliirh oiii\ one species is 

 mental organs found in lo\ver animals, and recurs in the j known, with spatulate snout, long but shallow (depressed) 

 .Selachians and Ganoids, as well as in the Salmonoids, peduncle of the tail, with the ujiper h^be of the caudal 

 Enchelymorphs, and Mormyroids among the Teleosts. tin |>rf)li)ngated into a hlameiitoiis appendage, and further 

 The family of the Stui'geon-tishes contains oidy characterized I)\ the absence of spiracles, belongs ex- 

 two, not very dissimilar genera, Sraphirhynchops and j clusively to the southern regions of North America. 



Gem.s acipenser. 



Fedniulc of the fail terete (not dejiressed) mid at least tir'iee as deeji iis the lateral laadal plates, a'hieh dn not 



meet fraiii each side of the liodif. 



'J'lie Sturgeons ha\e met with the same variet\- of 

 systematic treatment as the Salmons, and probably from 

 the same cause. They are anadromous fishes, breeding 

 in fresii water — a few, it is true, jiermanent inlialiitants 

 thereof — but else living in the sea. Their geographical 

 range is about the same as that of the Salmons, ex- 

 tensive enough to ofl'er a great vai'iety of plnsical 

 environments. The)' also show an inconstaiicy of form 

 fully comparable with that of the Salmons, and the 

 methods of their classification have been equally diver- 

 sified. In 1870 DuMEHiL described" 81 species of this 

 genus, among them (!"i from Amcric;i. In the same 

 year Guntiiei; ado])ted in his Cafaloe/ne only 19 spe- 

 cies, 9 American. -Iokdan and GiEisEirr'' (1883) re- 

 cognised only b species in Amei-ica, 2 from the Pacific 

 coast, 3 from the Atlantic: but the specific rank even 

 of these may be called in (picstion. 



The characters hitherto employed in the definition 

 of the species are subject to considerable variations. 

 It has long been known that the large body bucklers 

 of young Sturgeons are set closer together, and have 

 a longer, more pointed, and usually more hooked, cen- 

 tral spine, than those of older specimens. Their num- 

 ber was indeed recognised by Gunthei! as a valid 

 character, but varies in the common West European 

 and American Sturgeon, for example, between 1 1 and 

 13 in the dorsal row and between "26 and 34 in the 

 upper lateral row. Accoi-ding to Jokdan and Gilbert 

 these variations extend between 11 and 14 in the 



dorsal row and between '27 and 36 in the upper lateral 

 rows, according to Kroyer between 10 and 14 in the 

 former and between 26 and 31 in the lattei'. Fatio' 

 counted 1.") plates in tiic doi-sal i-ow. ( )f the small 

 plates in the skin between the large bucklers GuntiieI! 

 remarks, in the case of the common Sturgeon, that in 

 very young examples (which thus would be refeiTed 

 to the genus Haso of Dlmeril) the skin is provided 

 with very small rough ](oints; in older ones these ossi- 

 fications are broader, rough, substellate, and more (as 

 in the genus Acipenser of Dumeril) or less (as in An- 

 taceus of Dumeril) regularly arranged in oblique se- 

 ries''. According to Milner's observations' of the 

 American fresh-water Sturgeon, the large bucklers in- 

 crease in size until the fish has attained a length of 

 about 63 or ()4 cm., but afterwards diminish, partly 

 owing to the detrition of the spines, jiai'tlv by resorp- 

 tion of their margins, and both at the dorsal line and 

 the ventrjil margins they partially droj) off, or at least 

 become indistinct. Simultaneously with this process 

 may be obser\ ed a siiortening of the snout; and the 

 far greater relative length of the snout and its more 

 pointed foi'ni in young Sturgeons give the head an 

 appearance (piife different from that of older specimens. 

 The external sexual characters ai-e not nnirked, 

 and but little has been observed on this head. In the 

 Searui/a {Sherg, Acipenser stellatas) of the Black Sea and 

 its feeders, which species is characterized by a very long 

 and slender snout, the females, according to Heckel 



■" Nouv. suites a Buffon. Hist. Nat. Poiss., tome II. pp. S7 cett.. 



* Bull. U. S. Nat. Mus., No. 16, pp. 8."-,, celt. 

 ' Fne Vert. Suisse, vol. V, part. II, |i. 491. 



* The same observation liad already lic-mi made by Nii.ssdN OSh-anil. Fihi. F/.s-/-.. p. 702), thoug:li lie did not expressly point out its 

 systematic significance. 



■• U. S. Comin. Fitili an.l Fislier., Rep., p.-nl. II (1872 and 187.^). p. 70. 



