148 ■ Froceedings of the Royal Physical SorAetAj. 



brilliant as the ocelli of the Pectens. This is a feature in 

 most fish embryos. The eyes of these fish, however, continue 

 to increase in brilliance and beauty until they become a dis- 

 tinguishino- feature in the little creatures. The golden inner 

 iris of the female is more especially vivid. 



In the species of Lepadogaster, the embryos show a marked 

 irregularity of position ; that is, the eggs are affixed to their 

 station regardless of the future growth, which may develop 

 with its head or tail in any direction with reference to the 

 place of attachment. 



This also is observable wdth regard to other embryos, some 

 capsuled ova developing with the head downward, others 

 with the tail end affixed. 



One difficulty met with in investigating the embryology of 

 these fishes lies in the tenacity with w^hich the ova stick to 

 their place of attachment, no instrument I could invent 

 removing them without fatal injury. This narrowed my 

 investigations in some stages dow^n to the points that could 

 be examined through a pocket lens, and prevented more 

 careful microscopic drawings. 



At eighteen days, how^ever, the young of Zepadogaster 

 Decandolii showed marked indications of approaching the 

 active stage, although the sac was still of great size, and the 

 attachment to the slate too secure to be safely broken. Not 

 until the twenty-eighth day did any of them actually leave 

 the egg envelope and start upon an independent existence, 

 still with a large umbilical sac, w^hich did not interfere with 

 their activity of movement. 



In the case of Lepadogaster himacidatus, the young did not 

 possess such an important appendage at their entrance upon 

 an active existence, the sac, indeed, being comparatively 

 small compared wdth other fishes, and especially compared 

 wdth the other species of Lepadogaster. It would appear, 

 from an examination of the different species that develop a 

 sucking disc, that the most pronounced is Cydopterus lumpus, 

 seeing that, while it shows a completely-formed disc at the 

 length of 1 inch (as shown in Fig. 11), or say 25 mm., the 

 young of Lepadogaster Decandolii has no sign of a sucker, or 

 the concomitant habits, at the length of \ inch, or say 6-5 mm. 



