190 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



pal Hal glands. Botazzi worked on the physiology of the 

 nervous system and muscles, Jordan on the physiology of 

 movement, MacMunn, Moseley, and Briot on the " purple," 

 and Ariola on digestion. 



HABITAT. 



Aplysia punctata inhabits the shallow-water zone of the 

 sea down to a depth of about forty fathoms (Lo Bianco). Its 

 range extends from the Mediterranean to the Arctic Circle. It 

 is, however, extremely susceptible to the effect of foul or badly 

 aerated water, so that it occurs most abundantly on those 

 parts of the coast where the tide runs rapidly and the water is 

 uncontaminated by sewage or decaying matter. The best 

 place to look for it is on the beds of Zostera at very low T tides. 

 Its appearance is often sporadic, and whereas it may be very 

 abundant in a certain year at a definite spot, the same place 

 may not yield a single specimen when searched again the 

 following year. The same applies to the collection of specimens 

 with the dredge. At different places along the coast remarkable 

 incursions of Aplysia have occurred at intervals, as described 

 by Major Hunt in Torbay, and by other observers on the 

 Welsh and Manx coasts. Such an incursion was recorded by 

 Chadwick at Port Erin in July, 1916, when, after a severe 

 storm, hundreds of Aplysiae were thrown up on a small area 

 of shore within Port Erin Bay. They were in poor condition 

 and lay amongst pieces of decaying weed. Most of them 

 disappeared after a few days.* 



* The cause of the sudden appearance of Aplysiae in such numbers 

 is not known. It is probable that many die after breeding, but on this 

 occasion Chadwick saw no cordons of eggs. Possibly the stormy weather 

 tore off masses of weed, on which the animals were feeding, from the rocks 

 in deep water, and the Aplysiae were thrown up with the weed. Compare 

 also similar incursions of Aphrodite. 



