512 
to the modifications of Lituitesand Ancistroceras. It is completely 
uncoiled in the young, and the tip or apex has not even the open 
coiling of Ancistroceras, but is really an open or cyrtoceran curve. 
The annuli of the shell are also simpler in curvature and accord- 
ing to Remelé they have low broad dorsal and ventral crests and 
corresponding low broad lateral lobes. These phylogerontic curves 
appear to be acquired in the early ephebic stages, and therefore ap- 
pear earlier in the ontogeny than in Ancistroceras. 
The siphuncle is large and may be either dorso-centren, or about 
centren, and in &. Beyrichea is said by Remelé to be nearer to the 
venter than to the dorsum or ventrocentren. 
The list of species given by Remelé* is as follows: &. Beyrichia, 
Zaddachi, Oelandicum, damest, tenuistriatum. 
Rhynchorthoceras (?) dubitum. In the Dyer collection, Museum 
Comparative Zodlogy, there is a fragment that shows this genus 
probably occurs in the Niagara group of Indiana, but the younger 
stages are wanting and it cannot be surely placed here until these 
are known. ‘The first part of the free volution has the usual bands 
of growth with hyponomic sinus, these lines inclining orad and 
without inflections or with hardly perceptible lateral sinuses to the 
dorsum where they unite in low, broad saddles. 
There are also three inconspicuous low, broad costz on this part 
of the shell. ‘The form is a slightly compressed ellipse, the siphun- 
cle large, ventrocentren, the sutures have ventral and dorsal sad- 
dles and lateral lobes. The growth bands lose their inclination in 
the older part of this volution, becoming straighter on the sides 
and the hypomic sinus almost disappears. This last characteristic 
seems to place these fossils in this genus. 
LHolmiceras, n. g. 
Lituites precurrens sp., Holm, has open, discoidal whorls, like 
those of Angelinoceras latum, and closely resembles this species in 
form and proportions, both of the enrolled and outstretched whorls, 
but the lines of growth and annulations are very distinct. It has 
the four major sinuses in the lines of growth, as in Lituites, but the 
median dorsal crest is absent. The aspect shows the presence of 
another genus in this family and the sutures are also different from 
those of Lituites, having distinct ventral and dorsal lobes in the 
ephebic stage, with low, broad, almost straight, lateral saddles. 
* Zeitsch. Deulsch. Geol. Gesell., Xxxiy, 1882. 
