124 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



active early life — break up and disappear, and the free 

 tadpole becomes reduced to the sedentary sack-like 

 Ascidian. This life-history is a good example of 

 degeneration, and it also shows us that Ascidians are 

 derived from ancestors which were once related to the 

 backboned animals. 



There is one of the Tunicata which remains free- 

 swimming all its life, and has a backbone in its tail. It 

 is called Appendicularia, and we frequently catch it in 

 the tow-net in Port Erin Bay. 



The reports upon the Tunicata in our series are by 

 Professor Herdman, and the first of the L.M.B.C. Memoirs 

 is on " Ascidia." 



FISHES. 



(Figs. XXYI. to XXXI.). 



All fishes may be divided into two great classes — the 

 cartilaginous and the bony. To the former class belong 

 the well-known dog-fishes, sharks and rays, the skeletons 

 of which are composed of cartilage ; and to the latter all 

 those fishes, such as the bream, gurnard, mackerel, wrasse, 

 cod, plaice, sole, salmon, herring and conger, the skeletons 

 of which are composed, wholly or in part, of true bone. 

 There are about 150 different kinds of fishes found in the 

 sea around the Isle of Man. The great majority of these 

 are bony fishes, and less than one third of them are 

 marketable. Amongst the remainder are a large number 

 of small and inedible fishes, such as the blennies, gobies, 

 pipe-fishes (see fig. XXYI. 3), sucker-fishes, and stickle- 

 backs, which frequent shallow waters and are often found 

 under stones at low tide and in the rock-pools. Only a 

 small proportion of the total number can be shown in our 



