12 DR ARTHUR T. MASTERMAN ON THE 



by the above author, "more black pigment in the postero-lateral region," and, we may 

 add, on the head (cf. figs. 12 and 6), than the young cod of a similar stage. 



At 12 mm. (fig. 13) the ventrals have made their appearance as a minute pair of 

 papilla almost exactly below the pectorals. " Groups of black pigment corpuscles are 

 distributed alono- the base of the dorsal and the anal fins as well as over the brain, and 

 a similar series exists along the median ventral line of the abdomen. Black specks also 

 occur along the pre-maxillaries and the mandible" (M'Intosh). ver each side of the post- 

 anal portion of the body are finely scattered black specks, which become more prominent 

 in slightly later stages. Lastly, there is a series of delicate black bars across the caudal 

 rays which make a curved line of pigment on the caudal fin. Fig. 13 is very character- 

 istic of this stage, and there is some little change in specimens leading up to 15 and 16 

 mm. With increase in size the fins become separated by disappearance of the inter- 

 mediate embryonic fin and further growth of the true fin-rays. The posterior tip of the 

 notochord disappears and the caudal curve of pigment becomes fainter. The ventral 

 fins move slowly forward ; dots of black pigment appear over the median fins and the 

 lateral black specks become large and more numerous. These and other lesser changes 

 result in a stage, at 16 mm., of the appearance represented at fig. 14. The same general 

 distribution of pigment as in fig. 13 can be recognised, and these two figures could not 

 fail to serve for the identification of the young whiting from 1 1 to 20 mm. or more in 

 length. 



Along with the forward movement of the ventral fin appears that of the anus. 

 Thus in fig. 13 the latter is situated immediately below the commencing separation 

 between first and second dorsal fin, whereas in fig. 14 it is well below the middle of the 

 former. With the forward progress of the anus, the first anal fin becomes longer, and 

 new rays are continually added at its front end, so that the 18 of fig. 13 becomes 21 in 

 fig. 14, and by the time the stage of fig. 15 is reached, their number has increased 

 to 28. 



At about 16 mm. there appears a series of little black touches at the bases of each* 

 ray in all the median fins. These are very symmetrical, and are quite distinct from' 

 the little specks scattered on the fins between the rays. They are not found in the cod, 

 and are absent in the known stages of the haddock. They are, however, of constant 

 occurrence in the whiting in every stage, from 16 mm. by gradations of 1 mm. up to- 

 25 mm. and beyond. After this they appear to be lost in the general body pigment. 

 The caudal curve becomes fainter after 16 mm., and disappears at about 18 mm. 

 As will be seen by the accompanying Table, every stage with a gradation of 1 mm. 

 from 7 to 25 mm. has been examined, and there is little to note in the way of change 

 from 16 mm. onwards. The forward progress of the ventral fins and of the anus, with 

 its anal fins, continues, so that in fig. 15 the ventral fins, now elongated, are below the 

 occipital region of the head, and the anus is vertically below the first eighth of the first 

 dorsal fin. The lateral pigment is greatly increased, and the dorso- and ventrolateral 

 lines of fig. 14 have merged into it. At 20 mm. " traces of the median ventral black 



