122 THE VOYAGE OF H.M.S. CHALLENGER. 



Family M a c r u R i T)M. 

 Macrurus. 



Head generally with large muciferous ca"vities, most developed in the suborbital ring, 

 and continued into the praeoperculum and into the snout, which frequently projects more 

 or less beyond the mouth. The mouth may be inferior or subterminal and lateral, is 

 armed with small teeth, and the palate is toothless. A barbel at the symphysis of the 

 lower jaw. Scales sometimes typically ctenoid, sometimes cycloid ; no scaleless fossa 

 on the side of the nape. The second dorsal is always less developed than the anal, and 

 its anterior rays, or all of them, are more or less rudimentary. Gill-membranes slightly 

 united in front. Four gills with well-developed gill-laminae; no pseud obranchise. A 

 broad fold of the membrane of the gill-cavity stretches across to the terminal portions of 

 the first branchial arch, and renders the slit between that arch and the wall of the gill- 

 cavity much narrower than the slits between the arches. Gill-rakers of the first 

 branchial arch broad, low, cartilaginous bodies, generally armed with curved spines. 



Before the Challenger Expedition the known species of Macrurus were few in 

 number, and they were but sparingly represented in museums. Thus, when I gave a 

 general account of them in the year 1862, I knew from autopsy five only, and I believed 

 I recognised in them the types of three genera, which I distinguished by the form of the 

 snout and position of the mouth, by the size of the scales and modifications of the 

 dentition. 



The dredge of the Challenger secured more than one hundred and forty examples, 

 referable to thirty species, and proved that this type of fishes is not only one of the 

 most widely spread in the depths of all oceans, but also extremely abundant with regard 

 to species and individuals. These materials afforded the further evidence that the 

 characters on which I had relied for the generic groups of Macrurus, Coryphsenoides, 

 and Malacocephalus, did not possess the taxonomic value assigned to them, with the 

 exception of the modifications of the dentition, which, however, were capable of more 

 precise definition. 



With regard to the form of the snout and position of the mouth, there exists 

 every gradation, from the most specialised types, such as Macrurus japonicus and 

 Macrurus parallelus, to Macrurus longifilis, which may be regarded as representing the 

 original type whence the others were derived. Its head is compressed, well projjortioned, 

 formed by firm bones, the superficial of which enclose a muciferous system not more 

 enlarged than we find it in many surface fishes ; its snout is not more tumid or project- 

 ing than in the majority of surface Gadoids, and the wide mouth terminal and lateral. As 

 the muciferous cavities increase in width, the bones are expanded into thin lamella3 and lose 



