St. Andrews Marine Laboratory. 433 



Ova of the Short-spiaed Cottus (Cottus bubalis, Bloch). 



So little definite information lias hitherto been available 

 with regard to the spawning of this species, that in the recent 

 and excellent work by Mr. Francis Day the following account 

 is given : — " Breeding : In Greenland it has been observed 

 to deposit its eggs on the seaweed in December and January. 

 Its eggs are very small, and in this country are extruded 

 during the spring in the sand or pools in the rocks. The 

 male is said to make a nest of seaweed and pebbles for the 

 reception of the spawn, while h? is believed to watch over 

 and protect the young when hatched." On the other hand, 

 Prof. Alex. Agassiz observes that the ova of certain American 

 Gotti are pelagic. It was not till the 1st of March that a 

 female deposited its ova (PI. XVI. fig. 4) in the laboratory. 

 This specimen had been isolated and its movements some- 

 what limited, and it is probable therefore that the deposition 

 may have been hastened. A large quantity of faint pinkish 

 ova were extruded in a few seconds, and they adhered firmly 

 together, forming a mass like that of the lump-sucker (PI. XV I. 

 fig. 3), though they were individually smaller, viz. 1*5 millim. 

 in diameter. An examination of its ovaries shortly after- 

 wards showed that a few ova were still present. Subsequently 

 others deposited eggs of a beautiful roseate hue, of a deep 

 red or of a pale straw-colour. All adhered very firmly toge- 

 ther, yet leaving a series of cavities, so that the whole mass, 

 as in Cyclopterus, imbibes and retains water, a provision of 

 importance in the case of eggs deposited near low-water mark. 

 The egg-capsule is thick, tough, and resistant, and shows the 

 facets or processes by which it adheres to neighbouring ova. 

 This coat is seen to be minutely punctured under a high power. 

 None of the ova deposited in the tanks seem to have been fer- 

 tilized. Many reddish examples (in mass) were procured from 

 the rocks towards the latter third of March, and in these the 

 embryos were well advanced. 



This species is one in which the ova attain a nearly uni- 

 form size in the ovaries, and are extruded simultaneously. 

 At the full period, indeed, the ovaries are heart-shaped, only 

 a slight sinus occurring in the middle line anteriorly, while 

 the posterior end is bluntly conical. 



Armed Bullhead (Agonus cataphractus, L.). 



The ova of this species were nearly ripe in a specimen 

 trawled on March 12, in St. Andrews Bay, where they 

 abound amongst the sand. They had a pale salmon-colour 

 and a diameter of 1*3 millim. They are somewhat less re- 



