4 F. Ameghino — Geology of Argentina. 



A. Wagner ^ considered that Acanthoteuthis speciosa was referable 

 to Belemnoteuihis. Professor Huxley * concluded his excellent 

 summary of the literature bearing upon this subject as follows: — 



" Upon the whole it becomes plain that the Acanthoteuthes of 

 Miinster, so far as they are known only by hooks and impressions 

 of soft parts, may have been either Belemnites, or Belemnoleidhes, or 

 Plesioteuthes, or may have belonged to the genus Celceno ; and that, 

 with the evidence before us, it is impossible to say whether 

 Acanthoteuthis speciosa and Ferussacii belong to Belemnites or to 



Belemnoteuthis Though it is quite possible that either 



A. speciosa or A. Ferussacii may be really a Belemnoteuthis, we 

 have no certain knowledge of the fact" (p. 21). 



In his " Handbuch der Palaeontologie " (vol. ii, p. 520) Professor 

 Zittel referred Acanthoteuthis to the Octopoda; but in his "Grundziige 

 der Palaeontologie" (p. 443) he places the genus in the Belemno- 

 teuthidas and unites with it the phragmocone and pi-o-ostracum 

 which in his "Handbuch" (vol. ii, pp. 510, 511) he had designated 

 Ostracoteuthis. 



The specimen described above exhibits no trace of a phragmocone 

 or of a pro-ostracum ; but the general form of the body closely 

 resembles — excluding the phragmocone — that of an example of 

 Belemnoteuthis antiqua (from the Oxford Clay of Christian Malford) 

 in the British Museum Collection, the lappets at the posterior portion 

 of the body being comparable with the lateral expansions so well 

 shown in that specimen. But in Belemnoteuthis the ink-bag is very 

 near the ends of these lateral expansions, whereas in the example 

 of Acanthoteuthis described above, it is farther removed from their 

 posterior extremities and is relatively smaller. Still we think the 

 genus Acanthoteuthis is properly referred to the Belemnoteuthidas. 



EXPLANATION OF PLATE I. 



Figure of Acanthoteuthis speciosa, Miinster, from tlie Lithographic Stone of 

 Eichstadt, Bavaria. — a, arms, b, mass of calcite, probably indicating position of 

 head, c, triangular mass of calcite. d, ink-bag. e, f, leaf-shaped lappets. 

 g, booklets of arms, h, booklet enlarged twice natural size. — The figure is a little 

 less than one-half of the natural size. 



II. — Notes on the Geology and Paleontology of Argentina. 

 By Florentino Ameghino.^ 



UNTIL a few years ago it was believed that the Territory of 

 Patagonia was of an extremely simple and uniform geological 

 structure ; it was supposed that from the Colorado to the Straits of 

 Magellan, and from the Atlantic to the base of the foot-hills of the 



1 Op. cit., p. 820. 



- ''On the Structure of the Belemnitidaj ; with a description of a more complete 

 Specimen of Belemnites than any hitherto known, and an account of a New Genus 

 of Belemnitidte, Xiphoteuthis'' : Mem. Geol. Surv. United Kingdom, Figures and 

 Descriptions illustrative of British Organic Eemains, Monograph ii, 1864. 



* "Notas sobre Cuestiones de Geologia y Paleontologia Argentiuas " : Bol. Inst. 

 Geografico Argentiuo. vol. xvii, 1896, pp. 87-108. Translated, with Supplementary 

 Observations, by Arthur Smith Woodward. 



