432 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



III. General Considerations. 



The above list of zoeas and other larval stages of 

 Decapods is more notable for its relatively small extent 

 than for any great abundance of forms. 



Perhaps the most striking omissions (not of an 

 artificial nature, due to the removal during previous 

 examination of some of the larger forms, such as 

 Megalopa) which will be noticed in the lists are the young 

 stages of two common crabs in the Irish Sea, Cancer 

 fa gurus and Carcinas moenas. Not a single representa- 

 tive of the latter species, the common shore crab, was 

 found in the tow-nettings, and the former was only doubt- 

 fully present in the 1st zoea stage on the 13th of August. 

 This absence is probably due to the fact that both these 

 common species spawn in the late spring or summer, and 

 that they both spawn close in-shore. For it must be 

 remembered that the greater part of the most prolific 

 material was taken in early spring or late autumn in 

 localities several miles away from the coast. 



The most common Decapod zoeas were those of 

 Portunus puber and P. depurator and Hyas araneus, and 

 the three species seen to occur all through the spawning 

 period of the year. 



A zoea which probably belongs to Pilumnus 

 hirtellus was common in the autumn months, and present 

 in less abundance during the spring. There is little 

 doubt that this zoea is a Pilumnus, and the fact that only 

 P. hirtellus has been recorded from the Irish Sea makes 

 it highly probable that it is the young of that species. 

 Another record of interest is the zoea of a species of 

 Pinnotheres , which appeared very scantily in August. 

 During the past autumn it has been taken in comparative 

 abundance by Mr. Riddell in Cardigan Bay from the 

 " James Fletcher," and a description of it will 



