72 PKOCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



may be but an index of parallelism of modification with tbat group. 

 In this association, the mind reverts to Pelseneer's Pidmohranchia and 

 its allies, with a peculiar interest and suspicion. In this genus the 

 neomorphic " gill -fold," as in Planorlis and most Anci/lus, is present 

 on the left side, but in Ancyliis lacustris it is on the right. So great 

 a difference between species of a genus is by no means unknown on 

 the vertebrate side ; and one is led to inquire whether the Mollusca 

 possessed of this secondary organ of aquatic respiration may not be 

 disconnected forms, as certainly are some of the fishes which have 

 independently developed organs of terrestrial respiration and of 

 electrical discharge. And, to bring the matter home, permit me 

 to remark that the "Investigator" Pontiothauma, which, judged by 

 the characters of its shell alone, would be referred to a position 

 approximate to S/'pho, appears, on preliminary dissection by our 

 member, Mr. S. Pace, to be a Toxogiossate, and thus closely allied 

 to Pleurotoma. 



I will not pursue the question further, but rather again empliasize 

 the necessity for its investigation, under the firm conviction that 

 IMolluscan genera such as Fasciolan'a, Pkania, Engina, and Picinula, 

 the smaller species of Pleurotomidas, and Columbella, would well repay 

 extended inquiry into the anatomy of their soft parts, to say nothing 

 of the animals lying generally on the borderland of the Pulmonata and 

 Opisthobranchiata. I would remind you that the North American 

 genus ^'Acanthina" is now known to be an assemblage of species of 

 Purpura, Zat/rus, Ocinehra, and Trophon ; and I trow that in respect 

 to this far-reaching principle of convergence the class Mollusca will 

 be found second to none in interest. 



Advancement indeed has the Malacotomist to record. And when 

 ■we reflect that the classification of the Pelecypoda by their gills 

 has been of late widely accepted ; that in not a few of our most 

 recently described Pulmonata visceral characters of specific value have 

 been recognized ; and that for the diagnosis of the newest family of 

 Nudibranchiates ^ internal as well as external characters have been 

 found reqiiisite, — the spirit of Johannes Miiller, the father of Com- 

 parative Anatomy and a Malacologist, rises before our minds, as it 

 were, to demand its rights. 



I come now to the fulfilment of my last resolve, viz. to say a few 

 words upon our relationships to our fellow-zoologists, and upon the 

 position of our chosen subject in the r6le of science. The former is, 

 at any rate, a vexed question in the minds of some, though not of the 

 truly scientific. The species-man, weighing his minute characters, is 

 derided as a "mere systematist," the " morphologist," glorying 

 in the breadth of his horizon, barely condescending in some cases to 

 give him passing notice, entirely overlooking the fact that our 

 greatest generalizations in Biology are based on work in systematica 



* The IleJvIidic, E. Bergli, YerliauJl. k.-k. zool.-botan. Gesellseb. Wien, 

 Bd. xlv, p. 4. ■ 



