ANATOMY AND LIFE HISTORY OF MOLLUSCA. 119 



whole branchial organs of the animal. For instance, in Acmcea 

 alticostata, Angas, the filaments of the gill-plume are extremely 

 long and thin, attached on one side to the branchial artery which 

 is wide, and with a smaller artery running parallel at a short 

 distance, sometimes anastomozing with the main branch which is 

 the shaft of the plume. In the space between the two arteries, 

 the filaments are indistinctly marked and covered apparently with 

 papilla?. Beyond the smaller branchial artery the filaments 

 extend in long curved regular lines to the outer edge, where there 

 is a second artery at which they terminate. Beyond this there is 

 a margin of cellular substance, from which long, narrow, extremely 

 fine filaments extend and seem to be free, attached only to 

 the edge of the plume. 



Trochocochlea tceniata, Lamarck, is an interesting example 

 which can be obtained easily from almost any portion of the 

 extra-tropical Australian coast. The gill-filaments are grown 

 together, so as to form a broadly lance-shaped plate. They are 

 very long, but with such small cilia that high powers are required 

 for their detection. The circulating currents I have never been 

 able to see ; but one peculiarity is deserving of notice. On the 

 outer edge of the plume there are a few scattered, single, 

 cylindrical filaments, which extend from the free edge about a 

 fourth part of its greatest diameter. These have a kind of 

 spasmodic movement, sweeping round from side to side ; and 

 when they are watched with a moderately high power, it will be 

 seen that the tube opens and shuts with a sphincter-like contraction, 

 and a constriction a little within the extreme end. I have not 

 been as yet enabled to ascertain exactly whether this movement 

 was connected with the entry or exit of currents of water, but 

 the general impression left on my mind is that the movement was 

 that of suction, and water was taken into the interior of the gill. 



In making examinations of the gills, students need not be 

 restricted to such small species as those mentioned, for we have 

 commonly on our coasts large Mollusca, whose branchiae will 

 hardly require the aid of a common lens for their dissection and 

 examination, and only that of the microscope will be necessary 

 for minute physiological details. Haliotis ncevosa, Martyn, Turbo 

 (Senectus) gruneri, Phil., T. (Lunella) undulatus, Chenm., are 

 all very common on the south coast, and of large size. I was 

 once fortunate enough to secure a very fine specimen of Sepia in 

 Botany. The species may have been Sepia officinalis, L., at any 

 rate, it was about two feet long, and was a splendid subject for 

 dissection. The branchial cavity when laid open along the mesial 

 line, exposed a beautiful pair of pinnate gill-plumes at each side 

 of the ink-bag. The pinna? were given off from a stout stem, 

 which was not unlike in form to the shaft of a feather. The 



