509 
lines of growth, Holmiceras precurrens, sp. Holm. In 4. 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. ndet. (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 Zt. Ztwws, 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 Remelé.* Boll 
had originally used the name Ancistroceras in connection with 4. 
undulatum, the species which must be considered the type of the 
genus, but had subsequently abondoned its use, and this and his 
insufficient diagnosis was supposed by Remelé 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. Ndétling has also dem- 
onstrated that wsdu/atum 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. 
Remelé’s paper deals also with Lituites and he really divides the 
group of Lituitide 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. Schréder, in the paper quoted above, 
* Zeitsch. geol. Gesells., 1881, Pl. elxxxvii, ‘‘Strombolituites,”’ etc. 
} Arch. d. Verds. Freunde d. Naturg. Mecklenburg, Xi. 
