JRevieios — A. H. Foord's Catalogue of the Cephalopoda. 327 



umbilicus), and Nautilus, is proposed by one of us in substitution 

 for Trematodisciis, Meek and Wortlien, which was used by Hackel 

 for a genus of Eadiolariausi The name Trematoceras proposed by 

 Hyatt (Proc. Boston Soc. Nat. Hist. 1883, vol. xxii. footnote, p. 291) 

 in lieu of Trematodiscus is equally ineligible, because preoccupied, 

 for although the species described by Eichwald (Leth. Eossica, 1860, 

 vol. i. p. 1259)— Trematoceras discors — was a Bactrites, a generic 

 name once published cannot be again employed, even for a different 

 group, without risk of confusion." Prof. Hyatt retains for the 

 shells comprised in the present group the name Vestinautilus proposed 

 by Ryckholt ; but de Koninck pointed out that this name was 

 evidently founded upon an error of observation, and since it 

 " cannot be used in the sense intended by its author," Mr. Foord 

 agrees with de Koninck in treating Eyckholt's name as a synonym. 

 Mr, Foord reproduces the figures of the impression of the shell- 

 muscles of Goelonautilus, which appeared in the Geological Magazine 

 for November, 1889, and it is to be hoped that his examination of 

 the large number of specimens of Ammonoidea contained in the 

 National Collection will enable him to demonstrate also the form of 

 the muscular impression in some of the Ammonites. Several new 

 species of Coelonautilas are described, as well as of the genera 

 Temnocheilus and Solenocheilus. 



Then follows the genus Nautilus, of which, according to a table 

 given by the author in his Introduction, the Museum contains 88 

 species, viz. 5 Triassic, 30 Jurassic, 40 Cretaceous, and 13 Tertiary. 

 Mr, Foord remarks: "It might perhaps have been supposed that 

 a genus so rich in species as Nautilus is would have supplied many 

 subdivisions or groups of species ; but after carefully considering 

 the matter, I have come to the conclusion that such groups are in 

 the present case unnecessary, first, because the relationship in which 

 the species stand to each other is fully set forth in the remarks 

 appended to the descriptions of the species, and, secondly, because 

 such groups are apt to become very artificial, owing to the necessity 

 for frequent change in the selection of the characters upon which 

 they rest. It is true that there are often met with in the genus 

 Nautilus assemblages of species having many characters in common, 

 which are, however, too variable to found genera upon." 



Many of the species of Nautilus are comparatively new, having 

 been described by the author and Mr. G. C. Crick in the Annals 

 and Magazine of Natural History for April and May, 1890; some 

 are quite new, but the excellent figures which accompany the descrip- 

 tions of these species will greatly facilitate their identification. 



It is to be regretted that the whereabouts of some of Sowerby's 

 type-specimens is unknown. This is the case with Nautilus simplex. 

 On comparing the characters given by Sowerby with Mr. Foord's 

 description of his new species semiundatus, we think the author has 

 good grounds for suggesting the possibility of Sowerby's specimen 

 being a badly-preserved example of this new species. He adds 

 (p. 285), "Unfortunately, the siphuncle has not been seen in N. 

 semiundatus, and therefore it cannot be invoked in aid of this com- 



