Miscellaneous. 275 



hardened. We are told that the origin of the operculum is 

 very difficult to explain, that it represents a formation ^^ sui 

 generis,''^ and that its " finely striated horn- or chitin-like 

 substance " is to be derived from no part of the integument. 

 In order to remove the difficulties as to the origin of the 

 operculum, the author suggests the possibility that it may 

 arise from the envelopes of the egg which is placed upon the 

 back of the female at the time of sexual congress. 



If, in opposition to these statements of Klinckowstrom, we 

 allow my interpretation to stand, in accordance with which 

 the alveolus is originally an enlarged cutaneous gland, the 

 matter is settled in a simpler manner; for it was repeatedly 

 pointed out by me that in the cutaneous glands of tiie Batra- 

 chians the secretion, in consequence of thickening and 

 hardening, forms a kind of plug, which remains in the orifice 

 of the gland. I regard this " plug " of the cutaneous glands 

 and the " operculum ^' of the alveoli as equivalent formations ; 

 the operculum is, in my opinion, a plug of secretion developed 

 superficially. By this assumption tiie idea that the oper- 

 culum is a structure of a special kind is disposed of. 



Furthermore, in opposition to the view that the alveolus 

 arises through invagination of the integument, it might be 

 asserted that, were this correct, small mucus-glands must still 

 be present in the wall of the alveolus, since these must be 

 involved in the process of invagination of whole portions of 

 the skin ; yet no trace of such is visible. 



In conclusion, one may perhaps also recall the fact that a 

 process to some extent corresponding to the formation of 

 alveoli in Pipa takes place elsewhere in the case of Mammals. 

 Here, also, in the formation of the placenta the sprouting 

 tufts of the chorion do not grow into newly arising depres- 

 sions in tiie mucous membrane, but into the ducts of tlie 

 uterine glands, which were already in existence and now 

 undergo further modification. 



MISCELLANEOUS. 



The Bot-jiy of the Indian Elephant. 



At a meeting of the Mathematical and Natural Science Section of 

 the Imperial Academy of Sciences of Vienna held on July 2nd, 189H, 

 a communication was made by Prof. Friedr. Brauer to the effect 

 that, in conjunction with Herr Anton Handlirsch and with the 

 courteous cooperation of Herr Alois Kraus, Inspector of the Imperial 



