62 



Part TIT. — Twenty-fourth Annual Report 



long and upwards, differ in shape from the earstones of other species of 

 Gadus in being distinctly wider at the anterior end, instead of having the 

 upper and lower margins parallel or nearly so. The lower edge, which is 

 longer than the upper, is only slightly convex, and in some cases nearly 

 straight. A thick rib extends along the lower aspect of the convex 

 or inner side, as indicated by the photographs (fig. 2), but the stones 

 become thinner towards the upper edge. The upper edge is slightly con- 

 vex and shorter than the lower. Anterior end obliquely truncated. 

 Posterior end narrow, bluntly rounded, and terminating in a shallow 

 depression. Upper and lower margins usually irregularly but distinctly 

 crenulated. The pair of earstones represented on the plate by fig. 1 were 

 removed from a codfish 40| inches long; they measure about 21mm. in 

 length by fully 10mm. in depth.* Figure 2 on the same plate represents the 

 earstones of another fish 36 \ inches long, which measure about 18mm. by 

 fully 9mm. Below I give in tabular form the sizes of the earstones of 

 other fishes represented on pi. i. a. 







Earstones. 



Figures on Plate 



Length of Fish. 







i. A. 



Length. 



Depth. 



3 



15 inches. 



About 13 'Omni. 



Nearly 6 •Oram. 



4 



27* „ 



,, 15 - 5mm. 



7*omm. 



5 



21 „ 



,, 14 '5mm. 



About 6 '5mm. 



6 



10 „ 



,, 10\5mm. 



4 •Oram. 



7 



9 „ 



9'omm. 



,, 3"7mm. 



8 



51 „ 



,, 6 "5m in. 



,, 2*5nim. 



9 



4| „ 



5*7mm. 



2-3mm. 



10 



H „ 



,, 5'3mra. 



Fully 2 0mm. 



Gadus ceglefinus, Linn. The Haddock. PI. ii. a., figs. 1-5 and 9-16 ; 

 pi. iv., figs. 1 and 2. 



The earstones of tolerably large specimens of haddock have the upper 

 margin nearly straight, and parallel with the lower margin ; the crenula- 

 tion of this margin is not very strongly marked, but the lower margin, 

 which is slightly convex, is distinctly crenated. Among the haddocks 

 examined for the purposes of this paper, one was thin and emaciated, and 

 its earstones were not only comparatively narrow and elongated, but they 

 were also devoid to a considerable extent of the grooves and ridges so 

 characteristic of earstones of the normal type; this pair of earstones is 

 represented by fig. 3., pi., ii. a. 



A fairly large number of haddocks have been examined, and I find that 

 most of those about 8 or 9 inches long have their earstones obliquely 

 truncated in front, and that posteriorly the upper and lower margins con- 

 verge, though somewhat unequally, to form a narrow, blunt pointed 

 extremity. They are also laterally incurved, so that the hollow surface is 

 toward the outside, the convex side being inside, as in those of the codfish. 

 The earstones of the smaller haddocks are not so distinctly truncated in 

 front, and the upper and lower margins are not parallel, but converge from 

 the widest part near the anterior end gradually to the posterior extremity. 



* These earstones are thus equal to about the one forty-ninth part of the entire length 

 of the fish. In the other example specially referred to they are about the one fifty-first 

 part of its length. The earstones appear to be proportionally longer in the smaller fish. 



