DEVELOPMENT AND LIFE-HISTORIES OF TELEOSTEAN FISHES. 857 



was procured, the posterior edge of the hypurals not being quite vertical ; while the 

 upward bend of the notochord is in the form of a gentle slope. 



Various stages were obtained on the 11th October in the same haul of the net, the 

 earliest being like those last mentioned (1st October). The most advanced (about 19 or 

 20 mm. in length) had well-marked dorsal and anal fins, vertical hypurals, and just a 

 trace of a notochordal spike at the dorsal edge, and therefore intermediate between F 

 and G (1st July). 



These remarks would tend to indicate that, at least, two spawning periods, as already 

 known in regard to ova, occur in the neighbourhood. 



Some whitebait procured in the Thames in June measured from 38 to 40 mm., and 

 presented most of the adult characters. These perhaps represent the young of a late 

 autumnal brood, though, judging from those procured in St Andrews Bay in July, a close 

 approach must be made by the winter broods, especially in the warmer southern waters. 

 Meyer's statistics would further corroborate this view. Similar Clupeoids abound in St 

 Andrews Bay in March, and these may fairly be held to be the young of the previous 

 season. According to Meyer's statistics, such would be about 5 months old, but probably 

 they were from the ova of August, a period of seven months. 



The gradual change in the position of the anus, by the elongation of the region 

 between it and the tail, is noteworthy, as also is the relative position of the fins in the 

 young and in the adult. The latter, which has been called the migration of the dorsal 

 forward, was pointed out clearly by Sundevall and various subsequent waiters, and 

 appears to be characteristic of the Clupeidse. The recent remarks of F. Raffaele 

 (No. 125a) on this subject are of much interest. 



Clupea sprattus, L. — About the beginning of May numerous transparent ova having 

 a delicately reticulated yolk and somewhat thin zona radiata occurred in the bottom 

 trawl-like tow-net. They appear to be the same as Hensen first found in the Baltic, and 

 Cunningham obtained in the Firth of Forth west of Inchkeith, and which are described 

 and figured by him. Hensen truly indicates the pelagic egg of the sprat as having a thin 

 and transparent zona ; while the larval form, he states, is distinguished from that of the 

 herring by a slight flexure of the intestine.* Many are not quite round, their long 

 diameter being '044 inch, and their short diameter # 039. The reticulations of the yolk 

 (PL I. fig. 5) are very fine, and much less distinct than indicated by Mr Cunningham, the 

 margins of the sphere in an ordinary view presenting a confused series of lines. These 

 eggs occur in very considerable numbers, and are evidently those of an abundant species. 

 They are easily recognised from ova which resemble them in size by their translucency 

 and the colourless embryo. They develop very quickly, and the larva soon escapes as a 

 translucent form about 3*6 mm. in length, and, as Mr Cunningham says, is at first devoid 

 of pigment. It is a characteristic Clupeoid (PI. II. fig. 13), with the anus situated 

 posteriorly. The yolk has the same kind of reticulation as described above, and it is 

 comparatively large. Well-marked sense-organs are present on the sides, the last pair 



* Funfter Bericht der Komission z. wiss. u. d. deutschen Meere, 1887, p. 40. 

 VOL. XXXV. PART III. (NO. 19). 6 R 



