GADID^. 312 



Genus VI — MoTlLLA, Guvier. 



Onos, Risso : Mu-itelus, Stark : Gadus, Fleming. Giliata (yowig) Couclt : 

 Gvuchia {young) Thompson. Movella, Kanp. Hypsiptera, sp. Giinther. 



Branchiostegals seven : pseudobrancMce. absent. Body elongated, rounded in 

 front, compressed behind, upper surface of head flattened. Three or more barbels on 

 the snout, lips, and below the tnandibular sijmphysis. Teeth present in a band on the 

 jaws and vomer. Two dorsal fins, the first consisting (excepting the first ray) of very 

 slender rays lodged in a depression, the second fin elongated and continued almost to 

 the base of the caudal fin. A single anal. Ventral having from th.ree to eight 

 rays. Gaudal distinct from dorsal and anal. Scales minute. Goecal appendages 

 few or in moderate numbers. 



The adult fishes of this genus are commonly known as roclc-lings, from which 

 the young have been separated as macherel-midges, and termed Giliata by Couch, 

 and subsequently Gouchia by Thompson. Likewise Dr. Giinther has referred 

 some of his types of Hypsiptera Giinther (see page 303) to Gouchia argentata, 

 which is the young of Motella tricirrata. When Couch first proposed this new 

 genus of Giliata at the Linnean Society, " they hesitated to publish it, believing 

 that the fish was a young condition of some other known species " (Couch). The 

 young are uncertain in their appearance, for in some seasons only a few can be 

 detected ; while in others they are seen in countless multitudes. During March, 

 April, and even as late as June, they are found near the surface of the sea in 

 scattered communities, from one to twenty miles from land, and frequently several 

 schools join together. In stormy weather they are thrown on board vessels with 

 the spray, or drawn into fishing boats with the nets : they seek shelter during 

 heavy seas under the protection of any floating object, and are frequently seen 

 among the sea-weed, or under the protection of a medusa. These little fishes are 

 so sought after for food by predaceous forms as mackerel and bass, that they have 

 been termed" mackerel-midges," and when they grow larger assuming the Motella 

 or "rock-ling" size, they are likewise much relished, especially by conger-eels. 

 In an aquarium these fishes keep the first dorsal fin in a,lmost continuous motion, 

 similar to the fin movements in pipe-fishes, Syngnathus. The young, or mackerel- 

 midges, die almost immediately on being removed from the sea. 



Mr. Sim has recorded having captured on July 15th, 1868, at Aberdeen, 

 a small mackerel-midge which possessed seven barbels : it was transmitted to 

 Mr. Couch, but appears to have been lost ; consequently it remains doubtful whether 

 it was a distinct species or variety of a known form ; the additional barbels appear 

 from the drawing to have had their origin at the posterior nostrils. Some authors 

 have believed that the number of barbels are insufficient characters on which to 

 found species, and that the five- and the three-bearded roch-lings are identical. 

 Along the S.W. coast I have obtained three species of Motella, and also three 

 species of mackerel-midges which I believe to be their young stages. The young 

 M. mustela is brown with blue eyes : the two others are silvery white but darkest 

 alono- the back : the one I believe to be M. tricirrata has also a black axillary spot, 

 and a black mark on the ventral fin : the upper surface of its head flat : the young 

 M. cimbria is of a similar colour without the spots, its interorbital space convex, 

 and its head short. Dr. Giinther has separated from M. tricirrata some British 

 specimens which he believes appertain to M. macidata, Risso, giving as a reason 

 the character of their teeth, those in the upper jaw in the former being in a band, 

 whereas in the latter there exists an outer enlarged row, and this last species is said 

 to possess one less abdominal vertebra. These two very similar forms inhabit the 

 same localities, and the question naturally arises, can they be varieties of one 

 species or sexual variations ? All I have taken furnished with an enlarged outer 

 row of teeth in the upper jaw, or M. maoulata in the British Museum Catalogue, 

 are males. But although the uumb'jr examined is insufficient on which to base 



