38 EEPEODDCTION AND DEVELOPMETSIT OF TELEOSTEAN FISHES 



suggests some interestiug possibilities witli regard to tlie true syste- 

 matic affinities of these two genera. Callionymus belongs to a 

 group, Callionymina, which is classed by systematists in the family 

 Gobiidge, but which certainly forms an aberrant group of that 

 family. Callionymus is extremely different from any of the typical 

 Gobiidas ; it has a depressed form, no ventral sucker, has the eyes 

 close together at the top of the head, in accordance with its habit of 

 lying always on the sea-bottom on its flat ventral surface, and has 

 a multiradiate spine resembling a riding spur directed backwards 

 from its preoperculum. Uranoscopus similarly belongs to an aber- 

 rant group of the Trachinidse, to which our common weevers, 

 Trachinus draco and vipera, belong. All the Trachinid^ with few 

 exceptions have a backward-pointing spine on the operculum. 

 Uranoscopus possesses this spine, but whereas most Trachiuidae are 

 compressed from side to side, Uranoscopus, as its name implies, is 

 depressed from above downwards and has the two eyes directed 

 upwards and placed on the upper flat surface of the head. The 

 families Trachinidge and Gobiida3 are widely separated by Giinther, 

 the former being placed among the Gobiiformes, the latter among 

 the Cotto-scombriformes. Yet considering that the eggs have a 

 rare peculiarity in common, and that there are several similarities of 

 adult structure, it seems probable that Callionymus and Uranoscopus 

 are closely allied, and that either the Callionymina ought to be 

 included among the Trachinidte instead of among the Gobiidee, or 

 that the Callionymina and Uranoscopina together form a single 

 family, distinct both from the Gobies and the Weevers. 



In support of this suggestion it is to be noted that the ova of 

 typical Gobiidee are adhesive, not pelagic like those of Callionymus, 

 and that, although the ova of both Uranoscopus and Trachinus are 

 pelagic, those of the former have the reticulate marking and no oil- 

 globules, those of Trachinus have no marking and numerous 

 oil-globules. The ova of Trachinus have been described and 

 figured by George Brook in Lin. Soc. Journ,, vol. xviii, 1884, and 

 also by Raffaele in the paper so often cited. 



Clupea pilchardus (the Pilchard) and Clupea speattus (the 



Sprat) . 



The ovum of the pilchard has never yet been obtained directly 

 from the parent fish and artificially fertilized, and therefore the 

 absolutely certain knowledge based on the examination of ova so 

 obtained is still wanting. But it will be shown in the following 

 that a definitely characterised ovum is known, which I have traced 



