275 



Choffat : Materiaux pour I'etude stratigraphique et paleontologique de la 

 province d'Angola ; Memoires de la societe de physique et d'histoire na- 

 turelle de Geneve, tome xxx, no. 2, 1888, pi. 3, fig. 1). Youi' specimen 

 must be regai'ded as specifically distinct from A. mamillare, the siphonal 

 interstice between the outer tubercles being broader, the number of tuber- 

 cles in medium and comparatively large specimens smaller, etc., but it 

 must certainly be considered as an American representative of the group 

 of A. mamillare. You have already stated that it belongs to the Mani'd- 

 lati. Its general resemblance to A. laticlavium cannot be denied, but I 

 think its relations to A. mamillare are even closer. A. spini/erum in- 

 creases the number of Gault types in the Cretaceous series of the Queen 

 Charlotte Islands, and strengthens your opinion that at least a part of 

 the division C corresponds to the Gault." 



On receipt of this communication, a photograph (natural size) of the 

 large specimen collected by Dr. Newcombe was mailed to Dr. Kossmat 

 who acknowledged its receipt in the following terms : " Please accept my 

 thanks for the beautiful photograph that you have sent me. It is ex- 

 ceedingly interesting because it clearly shows that the adult form of the 

 Acanth. Stoliczkanum var. spiniferum is quite ditlerent from its middle 

 and younger stages. One of my friends, Mr. d'Anthula, who is engaged 

 in a study of the Cretaceous rocks of the Caucasus, has detected in the 

 Aptien strata (Lower Gault) of that region, a new species (not yet pub- 

 lished), the general relations of which have been unsettled up to this time. 

 Its septa remind one of Acanth. Martinii and A. mamillare, whilst its sculp- 

 ture has much in common with some species of Pachydiscus. But, com- 

 paring specimens with your photograph, the resemblance of the type of 

 sculpture in the adult stage (the young stage is not known in the Cauca- 

 sus specimens), the section, etc., is so great that there can be no doubt 

 that the two forms are allied and that both belong to the genus Acantho- 

 ceras and to the group of A. maynillare. Gabb's type of Acanth. Stolicz- 

 kanuTin is certainly related to the European A. Martinii, Orbigny, from 

 the Lower Gault (Aptien), and I think that your A. spiniferum,\s distinct 

 from both by its peculiar ornamentation, especially by the greater num- 

 ber of the tubercles in the same stages of growth, and by the compressed 

 outer tubercles which are longitudinally elongated in the direction of 

 the spiral, l)oth characters which connect it well with the group of A. 

 inam.iUare, as stated in a previous letter. To summarize all : I think 

 that the group of A. Martinii is represented in California by A. Stolicz- 

 kannm, whereas A. spiniferum, Whiteaves, is related to the group of 

 A. mamillai'e, and shows in adult age some peculiarities of sculpture that 

 have not been known before, but that can be observed in an analogous 



