162 



SCANDINAVIAN FISHKS. 



30"9 %, while in Gijmn. ventralis it is at least 33 %. The distance 

 from the beginning of the first dorsal fin to that of the second in 

 tlie first-mentioned specimen is 19'3 % of the length of the body and 

 64'5 % of that of the head, and in the female specimen of Gymn. 

 pistilliger 18-9 % and 62'6 % respectively; while in the male speci- 

 men of Gymn. ventralis it is 21 '8 % of the length of the body and 

 83 "i of that of the head, and, even in the specimen 43 mm. long, 

 tU; '„ of the length of the head. The base of the second dorsal fin 

 in llie male specimen of Gymn. pistilliger measures 82"6 % of the 

 length of the head, in the female 84'8 %: in Gymn. ventralis this 

 ratio may vary between 89 and 105 %. Tlie least breadth of the 

 iiilerorbital space in the male specimen of Gymn. pistillifjer measures 

 MVI "o of the least deptli (if the tail, and in the female 80-6 "o, 

 wliile in the mule the lengfli of the rays of the ventral fins, the 

 free part of which measures about -/j of their whole length, is 38 % 

 of the length of the body. Witli the exception of the last two cha- 

 racters and the singular dermal appendages, the other characters of 

 Gymn. pistilliger, however, indicate a retention, in common with 

 Gymn. ventralis, of juvenile eliaracters, a point which shows that these 

 species are very closely related. It is, therefore, natural that the 

 young specimens and the fry of both species should present a still 

 greater similarity in their characters. Thus, a male of Gymn. pistil- 

 l/i/er, CG mm. in length, from Kara Sea, has a granulation on the 

 tup of the head which is harder than the slight trace thereof which 

 occurs in the above-mentioned older specimens of that species, and a 

 specimen 48 mm. in length, from the winter-quarters of the Vega 

 Expedition, has an exceptionally small head, measuring only 26 % of 

 the length of the body, while the length of the maxillary bones is 

 :>4 % of the length ot the head. In every case, however, the other 

 characters should be sufficient to decide the species. The coloration 

 of the two species seems to be the same on the whole: but in the 

 male of Gymn. pistilliger the first dorsal fin is blacker, Avith more 

 <listiuct, round, white spots in one row along the superior margin, 

 in another shorter one at the middle of the fin, and in a lliird along 

 the base, M'hile the ventral fins liave distinct, black, transverse bands. 

 All these points, however, may sometimes be observed, though never 



so distinctly, in male specimens of Gymn. ventralis. Whether Gym- 

 nocantliiis pistilliger occurs in the basin of the Atlantic, west of Nova 

 Zembla, is a point on which we have no information. 



Gi/miiocanfhus ventralis is an arctic and circum- 

 polar .species. It is of fairly common occurrence off Spitz- 

 l)ergen, ^vhere it has been fonnd by all the Swedish 

 expeditions since 1837 (Sv. Loven), among the alga? 

 at depths sometimes as great as about 20 fathoms or 

 even more". It is met with in similar places on tlie 

 coasts of Greenland and Sil)eria. Since Lilljebokg 

 found it in 1848 off Scluiretskaja (Russian Fiiiinark), 

 it has also been met M'ith a few times off' the extreme 

 north of Norway. In 1850 a specimen from Hammer- 

 fest was forwarded to tlie Royal Museum by Mr. Bull. 

 In these regions, according to E.smark'', it lives at as 

 great a depth as 76 fathoms, or far below the lielt of 

 marine vegetation. It attains a size of from 215'' to 

 250'' mm. Its food, in all probability, is chiefly com- 

 posed of worms; but certain crustaceans {(jdnniKirithe 

 and Idotltetc) have also been found in its stomach l)y 

 CoLLETT. Fabkicius states, assuming that his obser- 

 vations refer to this species, that in Greenland it lives 

 on a sand}^ or clayey bottom, even where there is no 

 vegetation; that it is more cautious and quicker in its 

 movements than the true Cott'i : and that the female 

 lays its eggs a-mong the ulvte, while the male is sup- 

 posed to keep guard over them until they are hatched. 



Genus CENTRIDERMICHTHYS. 



Two distinct tJorsal fits. Skin iKikcd or irith spines or scales. Head middle-, ^ized. Uppermost preopercidar 

 spine bent or Jiraiidied or trith Utterttl spines. Palatine Iwiies ai/d roiiicr irith teeth. Branchiostegal metnhraiies 

 united, irith a free traiisrerse fold under the isthmus. No gill-slit liehind the fourth branchial arch. JRai/s in the 



anal fin less tlian 20. 



Obs. RICH.4RDS0N gave this genus its name in 1844'. Though 

 it liad previously been formed by Heckel' under the name Tracliydermns, 

 this name was unavoidably rejected, as it had already been used both 

 among insects and reptiles. In later times both the Scandinavian 

 species which belong to it, have received from Khoyer'' the generic 

 name Iceius. 



The genus Centrideriiiichth//s, with teeth lioth on 

 the palatine bones and on the vomer, so far as denti- 

 tion is concerned, forms tiie most decided contrast to 

 Gijmnocaiithiis of all the Cottoids; V)ut in other respects 

 is closelv related to tliat fjenus. The relations lietween 



" In 1801 it was taken in Hornsnnd at a deptli of (ill fathoms. According to CoLLETT it has been taken by the Norwegian Arctic 



Expedition in Magdalene Bay (N. W. Spitzbergen) at a depth of ,50 fatl s. 



'' Coi.i.ktt: Vid. Selsk. Forh. 1874, 1. e. 



'■ (Z', according to LtlTKEN. 



'' $, according to Coi.i.ett. 



' Voy. iSiilph., Fishes, p. 73. 



/ Ann. Wien. Mus. 1880, II, p. 159. 



'■' Naturh. Tidskr. Klihvii, 2:den Ra-kkes 1 :ste B. (lS4t— 45), p. 251. 



