Miscellaneous. 495 



MISCELLANEOUS. 



Note on the Anatomy and Physiology of the Pulmoniferous Mollusca. 

 By Dr. C. Semper. 



This memoir contains several interesting data upon the histology 

 of the Gasteropoda. The author has carefully studied the glandular 

 follicles of the skin, which had previously been much neglected. He 

 thinks he has ascertained that the external layer of the shell of the 

 Pulmonata, or the epidermis of the shell, which is probably composed 

 of conchioline, owes its formation to two different kinds (jf follicles, 

 whilst the inner layer of the shell would be formed by the precipita- 

 tion of calcareous salts secreted by the epidermic follicles of the ani- 

 mal. Semper appears to have had no doubt as to whether this inner 

 layer possesses an organic base. 



As regards the pedal gland, originally discovered by Delle Chiaje 

 and Kleeberg, and which Leydig and Deshayes regard as an organ 

 of smell, Semper agrees with Siebold in only considering it as an 

 apparatus destined to secrete a mucosity. 



Amongst many details relative to the circulation of the blood, and 

 the organs connected therewith, we shall only refer to one fact, 

 namely that the lung of the Pulmoniferous Gasteropods is destitute 

 of epithelium in the region where the exchange of gases takes place, 

 whilst the other parts of the organ, where the large vessels exist, are 

 clothed with a vibratile epithelium. 



If Semper's memoir presents many interesting details, it also con- 

 tains some manifest errors. In all the Gasteropoda the tongue is 

 supported by an apparatus composed of one or several cartilages. 

 Lebert, many years ago, recognized the nature of this organ, and 

 described and figured the cartilaginous cells. Semper asserts that 

 Lebert was mistaken, that there is no lingual cartilage, and that 

 what Lebert believed to be cartilaginous cells are only transverse 

 sections of muscular fibres. In this case Lebert would certainly have 

 been guilty of a gross mistake, and we might justly have been sur- 

 prised if so experienced an observer could have committed such errors. 

 Unfortunately for Semper, Lebert was perfectly right, and the lin- 

 gual cartilage really exists. Semper's error arises from his having 

 confined his researches to the Pulmonata, in which the study of the 

 lingual cartilage is really very difficult. If he had turned to some 

 Pectinibranchiata, such as the Neritince, the Buccini, or the Tur- 

 bones, or to some Cyclobranchiata, such as the Patellae and Chitons, 

 or even to some operculated Pulmonata, such as the Cyclostomata 

 and the Pomatice, he would have been careful not to accuse Lebert 

 of so grave an error. 



We are no more in accordance with Semper as regards the part 

 played by the tongue in deglutition. The description given by 

 Troschel of the functions of the lingual apparatus appears to be far 

 more natural and correct. In the trituration of the food. Semper 

 gives importance to the posterior papilla of the tongue, an organ 



