46;!- JMr. J. Alder on JefFreysia and Chemnitzia. 



ill the operculum, or represent it in his figure. But granting 

 that a process of some kind exists ; it cannot convert a spiral 

 operculum into an annular one, nor prove that those two forms 

 are identical. Apophyses, though rare, and differing from each 

 other in character, are found in the opercula of more than one 

 genus and more than one family ; taken alone, therefore, without 

 regard to peculiarity of form, they cannot prove even the family to 

 which a species belongs. Mr. Clark is wrong in saying that no 

 apophysis exists in any genus of the Littorinidce, for the Rissoina 

 of D'Orbigny has such a process, connected with a spiral oper- 

 culum. The soft parts of the animal, however, afford the most im- 

 portant characters. The position of the eyes in Jeffreysia "far back 

 in the neck, at the bases of the tentacula, in a line with them," is 

 brought forward in support of the union of this genus with 

 Chemnitzia, and I am challenged to produce any other of the 

 Littorinidce in which they are so placed. I know of none. The 

 position of the eyes of Jeffreysia on bulgings or prominences far 

 back in the neck, is, as far as I know, unique. Mr. Clark how- 

 ever adds another chax-acter and places them at the " bases of the 

 tentacula," a statement that may answer the purpose of accom- 

 modating them to the Chemnitzian chai-acters, but which is 

 surely incorrect. The eyes are at a considerable distance from 

 the tentacles. Besides they are on prominent bulgings, while in 

 Chemnitzia they are deeply immersed under the skin. The re- 

 semblance is too remote therefore to be of much value. 



A more important character now demands our attention. Mr. 

 Clark, after observing generally that my statements are incorrect 

 in most points, instances the proboscidal apparatus in Chemnitzia, 

 the account of which he pronounces to be wrong, " at least," he 

 says, " if any reliance is to be placed in M. Philippi's authorities." 

 But Mr. Clark might have known that PhiUppi's authorities have 

 been disproved long ago ; yet apparently in ignorance of this, he 

 is attempting to perpetuate, by stamping with his authority, what 

 other naturalists have considered an exploded error. The descrip- 

 tion of this animal given by Philippi is, in fact, only a literal quo- 

 tation from Mr. Lowe's generic character in the 6th vol. of the 

 'Annals of Natural History,' M. Philippi probably never having 

 examined the animal himself. Since that time Professor Loven has 

 very completely investigated this genus, and has given a short mo- 

 nograph of the Scandinavian species, with figures of several of 

 the animals, in the Proceedings of the Royal Swedish Academy, 

 the greater part of which he has republished in his ' Index 

 Molluscorum Scandinavife.' This latter Mr. Clark alludes to 

 in his last paper, and endeavours to construe the meaning of 

 the words so as to make the description agree with his own 

 and that quoted by Philippi from Lowe ; that is, to make 

 the proboscis of Loven correspond to the organ called by 



