Miscellaneous. 185 



general form and its relations with the siphon are the same as in 

 all the Ammonites. It is generally spheroidal ■when the turns of 

 the spire are free, and ovoid when they are contigiious. 



In the tetrabranchiate Cephalopoda which live in our present seas 

 and in all those which swarmed by thousands in the ancient seas, 

 the presence of an ovisac has never been detected. In Nautilus ?axdi 

 Aturia the siphon originates upon the inner walls of the first 

 chamber. It is completely closed at its posterior extremity by a 

 part of the calcareous prolongation of the septum which assists in its 

 formation. The external transverse cicatrix observed by Mr. Hyatt 

 can never have been in communication with the siphon ; its purpose 

 is still completely unknown. It has been indicated by M. Barrande 

 upon a great number of Silurian Tetrabranchiata. 



Thus it results from these observations that at the Silurian epoch 

 the tetrabranchiate Cephalopoda were as clearly separated from the 

 dibranchiate as at the present day. The only modifications that 

 we can recognize are of generic rank ; in fact the Ammonites 

 ■which, when young, have septa like those of Deroceras and Goniatiies, 

 appear to be derived from one of those tj'pes. — Comiites Rendus, 

 December 29, 1873, pp. 1557-1559. 



On the Endomycici. By the Rev. H. S. Goeham. 

 To the Editors of the Annals and Magazine of Natural History. 



GE>rTLEirEN, — My attention has been called to a brief notice you 

 have given of my descriptive catalogue of the Endomycici. The 

 question of classification, I venture to submit, is rather an experi- 

 mental than a logical one, and must be influenced by the amount of 

 knowledge possessed of the objects to be classified ; so that a group 

 of genera which fifteen years ago were united into a family may 

 now, by the addition of fresh genera, require subdi-viding into a group 

 of famihes ; and yet it may be convenient to retain as nearly as 

 possible the original title for the whole group, though of course the 

 patronymic termination must be altered. 



Had the re^viewer, however, been acquainted with Gerstiicker's 

 ' Entomographien,' he would have known that that author recognized 

 two ' groups,' " zwei sehr ungleiche Gruppen " — I. Endomychidas 

 genuini, II. Endomychidae adsciti. 



Whether it is illogical to attempt the union of these, or unne- 

 cessary to reconstruct the latter (which is a heterogeneous mis- 

 cellany), I wUl leave to those who follow me to determine. 



As your reviewer is so hard to please in the selection of names, he 

 should at least have quoted correctly the one he terms awkward. 

 I have no family " Paussidoidae," but one PaussoVdcidoe. 



The only genus in this family is Trochouleiis, Westw. Would 

 he have thought Trochoideidse less awkward or more expressive ? 



I am, Gentlemen, yours truly, 



H. S. GORHAM. 



Shipley, January 19, 1874. 



