NOTES ON THE YOUNG OF BLENNIUS GALERITA, L. 385 



The pectoral fins grow comparatively shorter with age, though subject 

 to considerable individual variation ; both these points appear suf- 

 ficiently in the table. 



The naricd tentacles are plainly visible in all examples from 13 mm. up. 



The intcrorhital "helmet^' increases with age, but may attain a very 

 different growth in two individuals of the same size. It consists of 

 a single leaf-like and broadish tentacle followed by several smaller 

 ones ; tliese latter seem to vary much in the period at which they 

 appear — though present in one specimen of 15'5 mm. they have not 

 yet appeared in another of 17'25 mm. 



A comparison with the figures given by Emery (1) of young forms 

 attributed to this species from Naples shows that (in addition to the 

 individual variations above alluded to) there is a very great difference 

 in the development of Atlantic and Mediterranean specimens ; a 

 Neapolitan example of 15 mm. (including caudal) shows no trace of 

 the interorbital " helmet " and has far longer pectorals than any of 

 the Cornish specimens, while a Neapolitan example of 23 mm. (in- 

 cluding caudal) still retains most of the black pigment on the pectorals, 

 which it is obvious must undergo their comparative reduction in size 

 at a much later period of growth than in the case of the Cornish 

 specimens. The differences in pigmentation and general form do not 

 appear, when allowance has been made for the different methods of 

 preservation, to be very great. 



Apparently in B. galerita, as in B. pholis (3 and 5) and B. occllaris 

 (2 and 3), the size and dark pigmentation of the pectoral fins increase 

 until a certain stage of growth is reached (possibly the stage at which 

 the young fish first begins to assume the habits of the adult), when this 

 increase is checked and the fins gradually assume the form and coloura- 

 tion found in the adult. 



The true significance of the " long-finned " phase of Blcnnius is by no 

 means certain. It has been suggested that it is of an ancestral nature, 

 but if so it is curious that Anarrhichas does not appear to pass through 

 such a phase. The groups of Acantliopterygii in which the pectorals are 

 most markedly developed are the Trigloids and Scoptenoids, forms 

 which are closely allied to one another, Ijut do not appear to be in any 

 way related to the blennies. 



If, on the other hand, the large size and dark pigmentation of the 

 pectorals are regarded as a purely transitory and adaptive character, the 

 " long-finned " blenny may be compared with the pelagic stages of certain 

 gadoids {e.g. Molva and Onos), in which the ventral fins are enormously 

 prolonged and deeply pigmented. It is not much use speculating upon 

 the origin and utility of such a stage, but the observation on Dactylop- 

 terus mentioned by Holt (4) certainly suggests the possibility that 



