■riiiiis.soMtiiii'iis. 



827 



the series extreuu-K- ditticult. \\ itliiii the Scuiidiiiaviaii 

 fauna the series coiitaiiis tlio lulluw iiiii' t'ainilies. 



I: Hinil i)art of the hack I'urnished witli an iKlipose tin. 



.l.' Ovaries without special oviduct com- 

 municating directly with their cavity: 

 the ripe egj/s fad into the ulidondnal 



cavity an<i pass thence throuLdi a geni- 

 tal pore. No phosphorescent spots on 



the sides of the hody Fam. Sdlinoiiiilir. 



B: Ovaries furnished with a complete ovi- 

 duct. Sides of the body furnished in 

 all Scandinavian forms with phosphore- 

 scent spots" .._ Fam. SropeluUr. 



II: Xo adipose fin .. Fam. < lnj>n<ia\ 



1am. salmonid.e. 



BoiJij of the fi/pl((il SdJmoii form nr more cniiipres.teih (ipproxinuited to the Roach or the Herriit;/ form. Scales 

 middle-shed or stmoll, rather frmli/ attached''. Xo phosphorescent spots on the sides of the hodi/. Dorsal margin 

 of tJie tail fariiishril a-itlt an adipose fii. 3fari/in of tin' appi'r Jaa- for and ia front In/ the internia.iillaries 

 and behind hi/ the ina.rillaries. Xo barbels. Air-bladder simple anil not connected a'ith the cranial cariti/. 

 Branchial earitij famished a-ith pseadrdtranchice. Ovaries open on the outside, n'ithout oridncts or u'ith oviducts 



openin;/ iiurards (into the abdominal cariti/). 



The fainilj' of the Salmons and Gwyniads is well- 

 known everywhere in the frigid and temperate regions 

 of the northern licniis|ilierc. In ihc southern iiemi- 

 spiiere, on the other iiand, only two genera occur, a 

 Capelin form (Befrnpinna Bichardsonii) belonging to the 

 fresh water of New Zealand, and two {':') Argentine 

 species, marine tishes of the same locality. The family 

 possesses more than ordinary interest l)oth from an eco- 

 nomical and a scientific point of view, to the economist 

 hecause the flesh of these fishes is one of the most 

 highly esteemed and most remunerative foods, to tlie 

 scientist because there is hardly any (jther' jiart (jf tiie 

 system where he is confronted \vith such ditticulties in 

 defining the limits of the species. This is due in most 

 cases to a plasticit\- and inconstancy of form, caused 

 beyond doubt bv the periodic migrations of the Saltno- 

 noids from the sea or the great lakes to running fresh 

 water. The economical value of these fishes has also 

 contriltuted to the said ditficulties. Wdiere they appeared 

 at certain seasons and certain places in enormous mass- 

 es, with one or other of their various dresses predomi- 

 nant, the fishermen gave these dresses different names 

 which the systematist had to explain, often merely after 

 examining solitary sjiecimens that were supposed to 

 represent distinct species. "Kart barn liar manga nainn'% 



" An extremely rare f(priii, Sudis atUuitivini, is an e.\ception. 



*" The genus Siilaiix (Albula c/iineiisis, Osbeck, Ostiml. Resa, 

 liuous scfiles (GtNTHER). 



' "A dear cliild has iniuiy names." 



•' Rech. Poiss. Foss.. vcl. V, p. lu:5. 



' Gl'NTHER. however, ciiiisidcrs tb.it this genus perhaps he!< 

 Mtlii/ol., p. 417. 



.says the Swedish proverb; and this rule has repeatedly 

 asserted itself in the nomenclature of the Salmonoids. 

 Tlie investigations of recent years, however, have elu- 

 cidated the significance of the variation of foi-in within 

 this family and the relationship to each other of the 

 more or less constant forms, and have thereby thrown 

 light upon the comprehensive question of the origin of 

 the species. 



The geological researches of Aoassiz'' have traced 

 the Salmonoid family back to the Cretaceous Period. At 

 that time there li\ed, where the green sand now lies in 

 modern \Vest[)halia, and \vhere the chalk subsided over 

 Southern England, several forms, which Aoa.ssiz referred 

 to the genera Osmerus and Osmeroides', the latter fur- 

 nished with scales resembling those of the modern ge- 

 nus Ari/entina. The evolution of the Salmonoid familw 

 we might hence conclude, began with marine fishes ot 

 the Smelt and Capelin type, with few pyloric appen- 

 dages or none at all, and its development advanced in 

 t\vo directions, 1) towards the Salmon and Charr, fur- 

 nished with teeth and with com})arativcly small scales, 

 2) towards the toothless and comparatively large-scaled 

 genus Coregonus. In both these directions of evolution 

 tlie pyloric appendages were more and more developed, 

 to assist these fishes in storing up a reserve supjily of 



p. 2.')7), however, is scaleless or has small, extremely thin, and deci- 



■d to the Scopelc.id family, liitrod. St'iil;/ Fish., p. 582: Hnndb. 



