Notes on the Larval Stages of Motella. 159 



and although it appears to occur all around the Scottish 

 coast, it is, so far as I am aware, not numerous in any 

 district. The occurrence of a large shoal of larvse off the 

 coast of Arran is therefore of especial interest. The fry of 

 the various species of Motella are known in the south of 

 England as maclccrel-michjes, probably owing to the fact that 

 mackerel and other predaceous fishes prey upon them. Day ^ 

 states that they occur in shoals from March to June, often 

 at a considerable distance from land. The genera Ciliata of 

 Couch, and Couchia of Thompson, are founded on these im- 

 mature forms ; whilst Giinther's Hypsi]jtera is an allied form. 

 Llitken refers it to the genus FliyciSy and more recently 

 Emery ^ has supposed Giinther's form to be the young of 

 Phycis mediterranea. 



The larval stages of an American species of Motella {M. 

 argentea) have been studied by Alexander Agassiz,^ who has 

 published an excellent series of drawings of immature speci- 

 mens varying from 4 to 34 mm. in length. The earlier 

 stages of development have also been studied by Agassiz 

 and Whitman * and myself^ 



The newly-hatched embryos of Motella are about 215 

 mm. in length, and are pigmented in a characteristic manner, 

 for the details of wdiich I must refer to the works already 

 cited. At this time the paired fins exist only in rudiment, 

 but the pectorals soon grow more rapidly than the ventrals, and 

 expand into relatively large rounded transparent organs a few 

 days after hatching. The ventrals, on the other hand, are at 

 first relatively small and narrow, and soon become pigmented. 

 One of the most interesting points connected with the life 

 history of Motella is the enormous development of the 

 ventrals into larval swimming organs, and their later 

 reduction to the normal type. 



^ Day, Fishes of Great Britain and Ireland, vol. i., p. 312. 



- Emery, Contribuzioni all' Ittiologia ; xv. Phycis mediterranea — Mittli. 

 Zool. Stat. Nap., Bd. vi., p. 159, pi. x., fig. 25. 



^ Agassiz, A., Young Stages of Osseous Fishes, pt. iii. — Proc. Amer. Acad. 

 Set., vol. xvii., pp. 294-296, pi. vii., and pi. viii. figs. 1-3. 



"* Agassiz and Whitman, Development of Osseous Fishes, pt. i. — Mem. 

 ;Mus. Conip. Zool., vol. xiv., pp. 39-43, pi. xviii., figs. 1-6. 



^ Brook, Development of Jfotella micstela — Jourii, Liun. Soc, Zool., vol. 

 xviii., pp. 298-307, pis. viii.-x. 



