G. C. Crick — Cephalopoda from the Tyrol. 445 



by Hyatt in his genus Arnioceras} If the affinities of the specimen 

 are really, as tiiey appear to be, with that genus, the fossil seems 

 to belong to the Lower Lias, though not to the lowest part of the 

 Lower Lias, that is to say, that it is not of Hettangian, but rather 

 of early Sinemurian age. 



The Belemnoid (PI. XXVI, Fig. 2)- is displayed in section upon the 

 uneven weathered surface of a small piece of grey limestone, which, 

 however, appears to be rather more dense than the matrix of the 

 Ammonite just described. The specimen is 53 mm. long, being truncated 

 posteriorly by the edge of the small piece of limestone on which 

 it is exposed. The anterior half of the fossil is occupied by the 

 alveolus. The guard as exposed is about 6-5 mm. wide, and therefore 

 appears to have been comparatively slender ; its sides are almost 

 parallel ; its posterior portion appears to be a little inflated, but 

 this may be due to the fact that the exposed surface is uneven, so that 

 the section which is exhibited does not lie in one plane. The angle of 

 the alveolus as shown is about 16°, but as the plane of section may 

 not be median, and may even be oblique, this angle may not represent, 

 but be somewhat greater than, the real angle of the phragmocone. 

 No portion of the phragmocone is preserved. The substance of the 

 guard consists of a blackish, crystalline, imperfectly laminated 

 material, the laminse being a little oblique, both from side to side 

 as well as from back to front of the specimen ; these are sometimes 

 accompanied by thin films of whitish calcite, but the guard does 

 not exhibit indications, either of a radiate structure, or of concentric 

 rings, or of a central axial line. No portion of the surface of the 

 fossil is shown, but, judging from the transverse section of the 

 truncated posterior portion of the guard, this appears to have been 

 smooth. The specimen is clearly referable to the Belemnitidae. The 

 sub-family Aulacoceratinae includes the four genera Aulacoceras, 

 Asteroconites, Bidyoconites, and Atractites, in all of which, except the 

 last-mentioned, the guard is variously ornamented; in Atractites it is 

 smooth. If, therefore, our conclusion as to the nature of the surface 

 of the guard is correct, the specimen, if referable to this sub-family, 

 can only belong to Atractites. But the angle of the alveolar cavity, 

 and the widening out of the portion of the guard around the alveolus, 

 lead to the inference that the fossil does not belong to the genus 

 Atractites. 



Notwithstanding the present condition of the structure of the 

 guard, the fossil appears to be referable to a subdivision of the genus 

 Belettmttes. The species is, however, quite indeterminable, though it 

 may be stated that the guard was evidently much more slender than 

 in such a form as Miller's Belemnites actitus.^ 



Notwithstanding their imperfect character these Cephalopods are of 

 importance with reference to the alleged existence of Liassic rocks on 

 the Tarntal mass. In 1859 Pichler* (p. 202) recorded the presence of 



1 A. Hyatt, Genesis of the Arietidce, 1889, p. 162. 



* British Museum (Natural History), register number C. 12114. 



3 J. S. Miller, Trans. Geol. Soc, ser. ii, vol. ii, pt. i, 1826, p. 60, pi. viii, fig. 9. 



* Adolf Pichler, " Beitrage zur Geognosie Tirols " : Zeitschr. des Ferdinandeums 

 fiir Tirol und Vorarlberg, 1859, Folge iii, Heft rai. 



