28G Appendices to Fifth Annual Report 



end of this epibranchial meets a considerably larger pharyngobranchial 

 than the first, which passes backwards, its tip almost touching the root 

 of the 1st, and a corresponding process on it underlapping (anterior 

 face) and being closely attached to the 1st epibranchial process. The 

 pharyngobranchial is also partly grooved for the gill filaments. Tie 

 median basibranchial of the 3rd arch also is ossified, but only the anterior 

 tips of the smaller pointed hypobranchials reach its posterior end, they 

 themselves in their main portion being separated from one another by a 

 central cartilaginous rod, which extends behind the 3rd basal piece. The 

 3rd cerato- and epi-branchials are nearly as the 2nd, and of similar form ; 

 but the pharyngobranchial, while firmly attached near its middle to the 2nd 

 epibranchial process, and grooved up to this point, is continued forwards 

 as far again, as a delicate needle-like rod lying close on the under surface 

 of the 2nd pharyngobranchial, and reaching nearly to the tip of the latter. 

 The 4th arch has a cartilaginous median portion, and no distinct hypo- 

 branchials ; but the proximal ends of the ceratobranchials are wider than 

 the others, each running forwards in a short point, which probably represents 

 the hypobranchials, the base of these processes being indeed less com- 

 pletely ossified than the remainder. The epibranchial of this arch is totally 

 different from the others, being a flat square bone with a short blunt process 

 from its distal outer corner, which is continued by a short cartilaginous 

 pharyngobranchial strip to connect it with the preceding epibranchial. 

 The 5th arch is represented by the single ceratohyal (lower pharyngeal) 

 (ph. 6), which articulates proximally with the median cartilage (which 

 latter is continued backwards as a posteriorly pointed cartilaginous 

 rod), and is attached distally to the posterior outer corner of the expanded 

 4th epibranchial. It is not grooved, and does not bear gill filaments. 

 Nearly the whole length of the ossified basibranchials is covered by two 

 elongated narrow scales of bone, bearing an irregular double row of small 

 teeth. The antero-internal faces of the epi-, cerato-, hypo- and part of the 

 basi-branchials of the first four arches support a band of tissue, giving 

 attachment to a series of long gill rakers. These are flattened from side 

 to side, pointed at their extremities, widened at their base, where they sit 

 on the arch, and are further secured by sending down partly across the 

 inner side of the arch a sharp narrow process similar to that found on 

 the cartilaginous rods supporting the gill filaments. Along their inner edge 

 is situated a double row of minute teeth. The gill rakers of the first arch 

 are the longest, those on its ceratobranchial division being about two-thirds 

 the length of that segment ; those on the other arches are only about one- 

 fourth of the length of the ceratohyals, being sufficiently long to fully 

 cover the interspace between the arches. The 4th ceratobranchial bears 

 in addition, and projecting backwards, a series of specially short rakers, 

 which are opposed to a row of similar ones on the anterior face of the 5th 

 ceratobranchial, and which occupy the place of the long rakers of the 

 other arches. 



The number of gill rakers on the first arch is about 66, there being 

 about 27 on the cerato, and 21 on the epibranchial portion; the second 

 arch has 60, 22 being on the cerato, 22 on the epibranchial ; the third 

 arch bears 46, 20 on the cerato, 16 on the epibranchial; the 4th arch 

 has 17 on the cerato, 12 on the epibranchial, 34 in all, while on its 

 posterior face it carries the 16 short rakers; those on the 5th cerato- 

 branchial number about 12. 



Apart from other anatomical characters (the swim-bladder, &c), the 

 herring shows a considerable similarity to the salmon in its skeleton. As 

 with the tail, so its skull seems to approach nearly to that of the salmon, 

 but the cranial ossification is much more complete. The arrangement of 



