902 PROFESSOR W. C. M'INTOSH AND MR E. E. PRINCE ON 



Gadoid of the size just specified, two hyaline plates pass obliquely on each side of the 

 snout — separated by a small interval from the maxillary rods and external to the 

 fronto-nasal cartilage. The maxillary elements, which at first are rod-like, become flattened 

 at this stage, and may appear, e.g. in Pleuronectes Jlesus, T \ inch long, as two lateral 

 hyaline scales. The parethmoids are more median, and lie as two cartilaginous cylinders 

 on each side of the stout ethmoidal (rostral) cartilaginous prominence. Above, the two 

 optic cups are well advanced, and are also cartilaginous. Beneath the central para- 

 sphenoidal bar in T. gurnardus, ^ 9 ¥ inch long, a hyaline plate is formed, possibly the 

 vomerine plate. In Labrus, ^ inch long, however, is a similar median plate of hyaline 

 tissue, but it is superior to the parasphenoid, and lies immediately under the point where 

 the optic nerves cross. In the goby, as Pouchet long ago noted, " the maxillary elements 

 appear in cartilage, and, when -^ inch in length, develop a superior crest by a " kind of 

 vegetation" of the cells (No. 119, p. 298), while further back an outgrowth in the form 

 of a horizontal bar probably represents the pterygoid. In transverse section, therefore, 

 two bars are present, an upper or pterygoid and a lower or maxillary bar. They have the 

 same character, but are somewhat lengthened in a form ^ inch in length. 



The mandible of the young wolf-fish, on emerging in January, presents a less advanced 

 condition than in the salmon. It forms a short conical process with a high cutaneous 

 flap on each side. Though its cartilaginous and muscular elements are partly developed, 

 it remains quite motionless, a feature doubtless connected with the widely-open mouth. 

 Meckel's cartilage forms on each side a long curved bar, which slightly dilates at the 

 anterior end, and terminates in a rounded portion — approaching that of its fellow in the 

 middle line. The mandibular cartilage in Callionymus, ^ inch long, is clothed on the 

 ventral surface with dense hyaline matter, which thins out on the sides of the mandible. 

 Outside the cartilage a separate hyaline scale exists, apparently developed in a deeply 

 stained mandibular fold of the integument. In the gurnard, ^ inch long, and in the cod, 

 T \ inch long, a similar extra-mandibular bar appears. It is very massive in the Gadoid, 

 ^ inch in length, as well as very prominent in section, since it and the surrounding tissue 

 of the flap stain deeply. An element is seen above Meckel's cartilage in Callionymus, 

 ^ inch in length, probably the symplectic. Posteriorly in Anarrhichas, the mandible 

 gradually dilates, and at the articular region forms a slight hollow for the rounded end of 

 the quadrate, the cartilage being continued further back as an angular plate, somewhat 

 broadly lanceolate in outline. The quadrate seems to be a narrow bar supported behind 

 by the pointed end of the symplectic — continuous with the hyomandibular cartilage. 

 Along with other changes, the mandible becomes much lengthened in March. 



At the seventh day in Anarrhichas, little elevations appear in the jaw, and towards the 

 end of the month one or two simple conical teeth, similar to those in the salmon, present 

 themselves in a line anteriorly. These increase in number, still keeping in linear order 

 in April, though the yolk is of considerable size. In the free condition the salmon 

 feeds readily in this state, the most abundant form found in the stomach being Cyclops. 

 Thus both fresh-water and marine larval fishes feed upon similar food. The teeth 



