258 Bibliographical Notices. 



indicative of great sensibility. It is continually contracting and 

 dilating both laterally and longitudinally ; bends quickly from 

 side to side ; twitches spasmodically ; and occasionally contracts 

 or constricts one part without altering the rest. The ejection of 

 the effete water from it is continuous while the organ is pro- 

 truded, and sufficiently forcible to make the current visible at the 

 distance of upwards of an inch from the orifice. The receiving 

 current however is intermittent. The siphon through which 

 this latter passes is a short truncate column, the edge of 

 which is set with about fifteen short incurved tentacles, separated 

 from each other at their bases by more than their own diameters. 

 This column, when withdrawn, first becomes oval, and then col- 

 lapses ; the sides coming into contact as the valves close over it. 



I am not aware that any one has included the Cockles among 

 the byssus-spinners. This little species however exercises the 

 faculty freely. It crawls up the glass sides of my aquarium, or 

 up a phial, six inches or more in a few hours, moving itself by 

 several diverging threads of varying length; and frequently, 

 when disturbed, hanging by one alone, after the others have 

 been cast ofi". I watched the process of spinning, which did not 

 differ from what I have observed in other byssiferous Conchifera. 

 The tiny white foot was protruded, and pressed against the 

 glass for a few seconds ; during which a slit, with mobile fleshy 

 lips, was opened in its upper edge, not reaching to the tip, but 

 terminating at about two-thirds of its length from the base. 

 When the foot was withdrawn, two threads were found attached 

 to the glass by minute sucking buttons. All the time of the 

 process I perceived that the terminal, ungrooved portion of the 

 foot, which was pellucid, seemed to be permeated by a central 

 canal through which a fluid was percolating. Such at least was 

 the appearance. 



EXPLANATION OF PLATE IX. 



Ftp. 5. represents Cardium exiguum, with the siphons extended; magnified 

 5 diameters. 



BIBLIOGRAPHICAL NOTICES. 



An Introduction to Entomology, or Elements of the Natural History 



of Insects. By William Kirby, M.A., F.R.S , F.L.S., and 



William Spence, F.R.S., F.L.S. Seventh Edition. Sm. 8vo. 



London, Longmans, 1856. /f^/ioaci* 



After the long period during #hien ^this work has occupied a high 



place in our entomological literature, almost all that remains for us 



to do is to announce to our readers the appearance of this " new and 



cheaper " edition of the • Introduction to Entomology.' It comprises 



only the first two volumes of the original edition, containing what may 



be termed the popular portion of the book, and is in fact a reprint of 



