i894. SEXES IN AMMONITES. 429 



ornamentation, in shape, in size, in septation, and in the processes at 

 the shell-aperture. 



First comes Munier-Chalmas, who, in the Compte vendti de la 

 Societc geologique de France (no. 14, p. 170, 1892), explains his views on 

 the subject. He considers that the males among Ammonites are 

 represented by certain " scaphitoid " forms, as he calls them, which 

 are distinguished by the following characters: — i. The last whorl is 

 more or less bent back [refrade). 2. The edge of the shell aperture 

 [peristome) is furnished with a double process — one auricle on each side 

 — (apophyse jugale). 3. The size is relatively small. 4. The evolution 

 of the septa is rapidly arrested. 



As types of these S cap hiti's -like Ammonites, Munier-Chalmas 

 indicates the following genera with which we are already acquainted : — 

 CEcotraiistes, Waagen ; QLcopiychius, Neumayr ; Sutneria, Zittel ; while 

 he himself adds, as new genera, Cadomoceras, of which the type-species 

 is A mmonites cadoinensis, d'Orb. ; Horiocevas, with type-species A . baugieyi, 

 d'Orb. ; and Creniceras which has for type A . renggeri, d'Orb. The 

 species belonging to these forms are considered by Munier- 

 Chalmas to be the males of other species, which are females. Thus, 

 CEcotraiistes genicular is, Waagen, is assigned as male to Oppelia subradiata 

 (Sow.) ; Horioceras bangieri (d'Orb.) is made to ally himself with 

 Distichoceras (n.g.) bipartitiim (Zieten) ; and so on. Why, if these 

 species really are males, generic names, none too happily invented 

 should be given to them, it is not easy to understand. Surely, among 

 Ammonites, as among higher orders of beings, husband and wife 

 should be known by the same name. 



This author also treats of the group of Ammonites allied to 

 A. humphriesiamis, under the name Coeloceras. This genus he divides 

 into males, distinguished by an " apophyse jugale," and called 

 Norviannites ; and females, which have no such " apophyse " and are 

 called Cadomitcs. Thus he links the following males and females : — 

 Cceloceras [N ormannites) bigoti to C {Cadomites) bigoti. 



„ „ sauzei to ,, ,, polyschides. 



„ ,, braikenridgii to ,, ,, siihcoronatum . 



„ ,, linguiferiiiii to ,, ,, datibenyi. 



The example set by Munier-Chalmas has recently been followed 

 by E. Haug, in a paper on " Ammonites des Etages moyennes" (Bull. 

 Soc. Geol. France, ^^ ser., t. xx., p. 298). This author has applied the 

 same criteria to the genus Sonninia, and has come to the conclusion 

 (p. 300) that the normal Sonninia: are the females, and that the group 

 of Sonninia sulcata, which contains forms not unlike Ammonites cycloides, 

 consists of males. He admits that the species of females far out- 

 number those of males, but expresses a hope that the missing 

 husbands will eventually be found. 



Let us now consider how far these somewhat extreme views, 

 which if true would lead to great complications, are consistent with 

 already known facts. 



