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lines of growth, Holmiceras prcecurrens, sp. Holm. In A. an- 

 guinum, however, it remains attenuated. The coiled portion of 

 the. shell has about three whorls coiled, and their attenuated propor- 

 tions and compressed form approximates more closely to those of 

 Lituites than to those of Ancistroceras. The close coiling in Ang. 

 sp. indet. (as figured by Angelin) of the nepionic stage shows also 

 more affinity for Lituites than for Ancistroceras. The figures of 

 Lit. lituus given by the same authors show also essential differences 

 from those of the true Lit. lituus, as figured by Lossen and Notling. 

 The coiled whorls are not in contact, not so compressed, free from 

 the large fold-like costations of that species and have the character- 

 istic lines of growth bending forward and with prominent ventro- 

 lateral crests near the apex of the whorl if correctly figured. Taken 

 altogether, the characteristics of the species of this genus show a 

 series of forms standing apparently between Lituites and Ancistro- 

 ceras. 



Ancistroceras. 



The name of Strombolituites was substituted by Remele.* Boll 

 had originally used the name Ancistroceras in connection with A. 

 undulaium, the species which must be considered the type of the 

 genus, but had subsequently abondoned its use,f and this and his 

 insufficient diagnosis was supposed by Remele to justify the sup- 

 pression of his name. Boll's type, however, being a good species 

 and a distinct genus, his name must stand in spite of his own desire 

 to suppress it and his defective description. Notling has also dem- 

 onstrated that undulatum has a closed spiral for one and one-half 

 whorls (said by him to be about two whorls). This is compressed 

 elliptical in the nepionic, and becomes more or less quadragonal 

 near the end of the spiral, assuming very quickly the circular form 

 after this. 



Remele' s paper deals also with Lituites and he really divides the 

 group of Lituitidse into three genera, since he endeavors to limit 

 the name of Ancistroceras to the forms which he subsequently 

 described as Rhynchorthoceras. 



The genus Ancistroceras differs from Lituites, according to 

 Notling, in having only three sinuses, a ventral and two lateral 

 sinuses in the lines of growth and aperture, the dorsum being oc- 

 cupied by a broad low crest. Schroder, in the paper quoted above, 



* Zeitsch. geol. Gcsclls., 1881, PI. clxxxvii, "Strombolituites," etc. 

 t Arch. d. Verds. Freundc d. Naturg. Mecklenburg, xi. 



