The Egg and Larva of Callionymus lyra. 



By 

 J. T. Cnnniughaiu, M.A. 



With Plate V. 



The egg of this species has been described and discussed by 

 Professors Mcintosh and Prince, by Mr. E. W. L. Holt, and by 

 myself.* Raffaele, in his paper in the Mittheilungen of the Naples 

 Station, vol. viii, described the yolk in the ovum of Callionymus 

 festivus as having a peripheral layer of yolk-segments, but no 

 reticulated marking on the surface of the vitelline membrane ; while 

 all we English observers have agreed in stating that the egg of 

 Callionymus lyra, our common dragonet, has a reticulated marking 

 on the vitelline membrane, but no yolk-segments. I was, therefore, 

 very much surprised, in examining some eggs of this species from 

 the tow-net this year, to find that there actually was a peripheral 

 layer of yolk-segments, which had hitherto been overlooked. 



Raffaele states that in Callionymus festivus, the Mediterranean 

 species, the yolk-segments extend all round the yolk from the 

 beginning, before it has been enveloped by the blastoderm. Whether 

 this is correct in C. festivus or not, it does not apply to C. lyra. In 

 the ovum shown in PI. V, fig. 1, which was taken in the tow-net on 

 May 14th, 1891, the blastoderm has spread over about one third of 

 the circumference of the yolk, and the layer of yolk-segments ex- 

 tends beneath the blastoderm and somewhat beyond it, but is absent 

 from the opposite pole of the yolk. An egg of the same species at 

 a later stage, in which the yolk is completely enveloped, and Kupffer^s 

 vesicle has appeared beneath the posterior end of the embryo, is 

 shown in fig. 2, and it will be seen that at this stage the external 

 subdivided layer extends over the whole of the yolk. Thus the 

 layer of yolk-segments in the egg of C. lyra is at first confined to 



* See Ann. and Mag. Nat. Hist., Dec, 1885 j Memoir by Mcintosh and Prince in Trans. 

 Roy. Soc. Edinb., vol. xxxv, pt. 3, 1890; my paper in this Journal, vol. i, p. 21; Mr. 

 Holt's Memoir in Sci. Trans. Roy. Dublin Soc, vol. iv, ser. 2, No. 7. 



