PAL^ONTOLOOICAL NOTES 



AND 



DESCRIPTION OF NEW SPECIES. 



1. Belemnites pr.ematur.us, Tate, Geological Magazine, Vol. vi., p. 



166 (1869). 

 Description. — Guard slightly sub-hastate, terminating in an acute central 

 point, contracted in all regions about the alveolar apex, and tapering very 

 gradually to the point. On the lateral faces of the anterior part of the guard 

 there are two distinct furrows, which extend to about the middle part. Axis 

 apparently straight. Phragmacone in its transverse section sub-oblong, the 

 dorso-ventral diameter being the longer. Extreme length '35 inch ; length of 

 axis, so far as traceable, "II inch. 



Geological Position. — Zone of " Ammonites angu- 

 latus," Lower Lias, Island Magee, Co. Antrim (2 Speci- \ I 



mens ; R.T.) 



Remarks. — The only other Belemnites in the Lower I 



Lias of Ireland are B. acutus, and B. pencillatus, which a V 



occur in the marls at Ballintoy, at a much higher horizon 



, ,-, ,. , ,-, , a - Outline, nat. 



than the shelly limestones whence B. prcematurus has been b. Enlarged. 



obtained. Naturally the question arises, may not this form be the young state 

 of one or other of these species ? The presence of lateral furrows in B. prce- 

 maturus precludes such a relationship. The affinity to B. clavatus, Bl., is 

 more obvious, but it has not the elegant fusiform outline of the young of that 

 species. Professor Phillips (Geol. Mag. Vol. vi., p. 239) remarks, that B. 

 prcematurus must certainly be distinguished from every variety of B. clavatus, 

 and may prove to be closely allied to B. pencillatus, which is by no means 

 always deprived of lateral furrows. 



B. prcematurus was published by me as the oldest-known British Belemnite, 

 but Mr. C. Moore had obtained a very small conical specimen from beds im- 

 mediately above those which yield Oslrea liassica ; and the Rev. P. B. Brodie 

 "a mere fragment from the insect beds (' A. planorbis 1 zone,) at Bruton. " 

 Neither of these older specimens have received specific names. 



2. Ammonites MacDonnelli, Portlock, ■ Geol. Surv. Deny, p. 134 (1843). 



Appears a good species ; it has the general form of A. planorbis, with 

 a thin prominent keel, and distant, faint, sigmoidal ribs on the outer whorl, in 



