58 THE FRESH-WATEK FLSIIES OF EUROPE. 



The spinous part of the dorsal fin is feebly developed, and the spines are 

 flexible. The ventral fins sometimes unite into a sucking disc. This family 

 includes about thirty genera of small carnivorous fishes, which frequent 

 shores in temperate and tropical regions, and sometimes live in fresh waters. 

 Among these fishes are some interesting types, such as the Feriopklhalnius of 

 the tropics, which at the ebb of the tide leaves the waters, and hunts for 

 Crustacea and small animals in the mud. The several genera of Gobiida 

 are distinguished chiefly by the condition of the ventral fins, which may 

 be united into one fin, or remain separated, as well as by the presence or 

 absence of scales, and the condition of the teeth, and gill-openings. 



Lairunculns pellitcidus is a small Goby, which lives for one year only, 

 and in Europe is the only instance known among the vertebrata of life thus 

 limited. 



Gobius is the only genus in the family which has fresh-water representa- 

 tives. The genus is distinguished by having a scaly and somewhat elongate 

 body. Teeth are in several series in the upper jaw, conical and fixed. The 

 anterior dorsal fin usually has six flexible spines; the posterior dorsal fin 

 is often more developed than the anterior dorsal. The anal fin is beneath, 

 and corresponds to the second dorsal, and both terminate considerably in 

 advance of the caudal fin. The ventral fins unite to form a disc which 

 is not attached to the abdomen. The gill-openings are vertical. There are 

 no pyloric appendages to the intestine. According to Giinther there are 

 nearly three hundred species of Gobies. 



Gobius martensii (Gunther). 



I D. 6, 2 D. 1/lU, A. 1/7—8, V. 10 = 5/5, P. 13—14,0. 3— 4/13/3— 4. 



In this fish (Fig. 25) the anterior extremity of the head is eonvexly rounded. 

 The head measures about one-quarter of the total length ; it is longer than 

 broad. The greatest breadth is about equal to the greatest height of the body of 

 the fish. The eye is placed near to the frontal outline, and has a diameter 

 of one-fifth the length of the head, is separated by its own diameter from 

 the other eye, and is in the anterior half of the head. The well-developed 

 muscles give a swollen aspect to the occi[)ital region and to the cheeks. The 

 gape of the mouth is widened, and the mandible is sometimes longer than 

 the pre-maxillary. In the maxillary and pre-maxillary bones the teeth are 

 arranged in parallel rows, but those of the first row in both jaws are some- 

 what longer than the others. There ai'c teeth on the pharyngeal bones. 

 The nares are unusually small, near to the orbit of the eye ; the posterior 

 narine has no valve. 



