308 Prof. M. Schultze on the Genus Cornuspira. 



careous-shelled, they must be called Cornuspira, and not Spi- 

 rillina. 



If the figure given by Ehrenberg of his Spirillina vivipara be 

 such that Williamson was to a certain extent justified in putting 

 it with my figures of Cornuspira, and supposing that Ehrenberg 

 might have deceived himself with regard to the presence of 

 silica (in which case I should likewise have had no doubt as to 

 the identity of the two forms), still the separation of the two 

 genera must be most decidedly retained since Ehrenberg has 

 recently described several new species of his genus Spirillina, 

 and now arranges them among the Folycystinse, therefore again 

 with organisms possessing a silieious lorica*. These descriptions 

 are of far later date than my book on the Polythalamia ; and as 

 Ehrenberg on this occasion does not mention my genus Cornu- 

 spira (although, as we shall soon see, it was well known to him), 

 there can be no doubt that he maintains the genus Spirillina as 

 perfectly distinct from Cornuspira, and that Williamson there- 

 fore cannot reckon upon Ehrenberg's acquiescence when he 

 places the two generic names together as synonyma. There are, 

 in the sea, Planorbiform ilhizopodous shells of calcareous nature ; 

 these are to be separated, as Cornusjnra, mihi, from similar shells 

 of silica, the SpiriUince of Ehrenberg. 



Ehrenberg, indeed, has also found something to urge against 

 my genus Cornuspira'^. He says that it is upon young states 

 of larger Polythalamia, which are abundant everywhere, that I 

 have founded a new genus, to which all title to stand is denied ; 

 and the indiscretion with which I have fallen into this error is 

 the greater, as I myself have admitted that the Agathistegia in 

 their earliest stages are not distinguishable from my Cornu- 

 spira. 



It is indeed difficult to believe that Ehrenberg can have been 

 serious in making this assertion, which, as we shall see, is quite 

 untenable. It is clear that we have here to do, not with inter- 

 pretations or opinions upon organic structure — not with the 

 organization of the Rhizopoda or the like (upon which, as is 

 well known, my opinions and Ehrenberg's are very wide apart, 

 and to dispute about which with Ehrenberg is the less my 

 design, as he has never adduced any new observations upon the 

 soft parts of the Rhizopoda in confutation of my statements) 

 — we have here to do only with shell-formation. Here Ehren- 

 berg moves in a domain in which he has been actually and 

 continuously active, and in which he may lay claim to the repu- 

 tation of a weighty judge. 



* Monatsber. der Akad. der Wiss. zu Berlin, 1857, pp. 574, 560 ; 1858, 

 p. 35 : see also p. 332. 

 t Monatsber. 1858, p. 332. 



