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Appendices to Fifth Annual Report 



remaining however of great thinness, and having a thickened bar along 

 their ventral edges. At their posterior ends they become much thicker, 

 and form a strong nodular-like head for articulation of the fin. At this 

 point they are closely approximated and attached by tissue to each other 

 by their sharp disc-like inner and ventral edges. A slight hollow on the 

 outer posterior end of the head forms an articulation for the pelvic fin. The 

 nine fin rays are similar to all the others ; but while articulating by their 

 heads almost directly with the innominate bone, there lies deep between 

 the bases of the rays a series of five small ossicles, similar to the arrange- 

 ment found in the pectoral fin. These are found in the fry to be relatively 

 larger than in the adult, where they may be rather obscure, and the first 

 (dorsal or anterior) one is wholly in connection with the first ray only. 



The Skull. 



The cartilaginous skull of the adult herring may be said to extend only 

 from the anterior auditory region as far forwards as the front of the nasal 

 capsules ; for posteriorly almost the whole of the cranial roof is absent, 

 and the remainder of the brain case is almost entirely replaced by the 

 strong otic and occipital ossifications, internal to part of which (part of the 

 pterotic and epiotic) only a small amount of cartilage remains unossified 

 (PI. XVII. fig. 19; PI. XVIII. fig. 22), appearing here and there on the 

 external surface of the skull, as narrow strips between one or two of the bones 

 composing it (PI. XVIII. fig. 23). But for a small thin piece of cartilage 

 the whole upper surface of the cranium, after removal of the frontal bones, 

 would be one huge fontanelle (PI. XVIII. fig. 22). Over the brain, and 

 covered by the frontals, this cartilage appears as a small triangular-shaped 

 piece covering the thalamencephalon and pineal gland, and connected 

 posteriorly by its backwardly prolonged apex, with an anterior median 

 process of the supra-occipital bone (fig. 22, s.oc). The other angles of this 

 cartilaginous triangle are connected with the tips of the alisphenoid bones, 

 and the whole, therefore, divides the upper cavity of the skull into three 

 fontanelles — two large and lateral over the optic lobes, hind brain, &c, 

 and one small and median over the fore-brain. 



Anterior to the auditory region, and closely invested above by the 

 frontals, the cartilage is continued forwards above the interorbital septum 

 as a shallow roof as far as the antorbital region, where it suddenly becomes 

 deeper, passing downwards in front of the orbit, and extending forwards 

 beyond the nasal region as a nearly trihedral mass excavated on each side 

 to form the nasal capsules (PI. XVII. figs. 18, 19). From its ventral surface 

 there passes backwards to beneath the middle of the orbit a narrow median 

 strip of cartilage (PI. XVII. figs. 18, 19, trie), on which is moulded the 

 parasphenoid (PI. XVII. figs. 18, 19, eth.), this being the only remainder of 

 the trabecular cartilage here. The antorbital cartilage terminates anteriorly 

 in an ossified median mass, slightly behind which stands out on each side a 

 pair of cartilaginous nodules (the cornua) (PI. XVII. fig. 18, cor,). Behind 

 the nasal cavities there also projects laterally on each side a cartilaginous 

 ethmopalatine boss (PI. XVII. figs. 18, 20, 21, ethpal.). Most of the dorsal 

 surface of this cartilaginous region is raised into a slight median elevation, 

 and is covered only by the skin, the frontal bones and ethmoidal ossifications 

 investing its lateral portions (PI. XVII. figs. 18, 20). The upper portion of 

 the cartilage is centrally excavated to form an elongated cavity open only 

 at its posterior end, and reaching from the anterior upper part of 

 the orbit to beyond the middle of and close above the nasal capsules 

 (PI. XVII. fig. 19, m.cav.); in this cavity lie and are attached towards its 

 anterior end the superior oblique muscles of the eyes. The actual inter- 



