296 CEPHALOPODA. 



the winged insects of the sea, reminding us, in their 

 free circular movements and crepuscular habits, of 

 the gnats and moths of the atmosphere ; they shun 

 the light, and if the sun is bright you may look in 

 vain for them throughout the live-long day. It is 

 only as day declines that their true time begins ; and 

 thence onwards the watches of the night may be 

 kept by observing the contents of the towing-net, 

 as the hours of a summer's day may be by the floral 

 dial. The Cleodoraz are the earliest risers. As the 

 sun sets, Hyalsea gibbosa appears, darting about as if 

 it had not a moment to spare, and indeed its period 

 is brief, lasting only for the Mediterranean twilight. 

 Then it is that Hyalsea trispinosa and Cleodora subula 

 come up. Some species retire early, while others are 

 to be met with only during the midnight hours, and 

 in the darkest nights. There are, however, a few of 

 irregular habits, who manage to keep it up the whole 

 night through. All, however, are back to their 

 homes before day surprises them." 



CHAPTER XX. 



SEVENTH CLASS OF MOLLUSCA. 

 CEPHALOPODA.* 



the strange combination of characters em- 

 ployed to designate the last and highest order of the 

 Mollusca, the student will, no doubt, be prepared 

 to anticipate something remarkable in their habits 

 and appearance ; nor will his expectations be disap- 

 pointed. 



Their body is enclosed in a muscular sac or bag, 

 which in many species is provided with fleshy fins 

 that project on each side. Their head is furnished 

 with a pair of large staring eyes, and surmounted by 



* /ce4>aA^, cephale, the head ; TTOVS, voSbs, pous, podos, a foothead- 

 footed. 



