10 



TYPE AMMONITES— VI Feb. 



toceras distans shows much disagreement with that of his S. crassum, 

 but full agreement with those of species of Allovirgatites. On the first 

 ground the conclusion is reached that, whatever else it may be, Dr. 

 Neaverson's distans is not a Sphinctoceras, and, on the second, that unless 

 there is some character other than suture-line to weigh heavily in the 

 balance, it belongs to the genus Allovirgatites. 



The slight differences in the proportions of Allovirgatites are easily 

 accounted for. There are, first, indistinctness in the illustrations and, 

 secondly, differences in the base-line. Thus the base-line in a com- 

 pressed-whorled species like A. tutcheri departs little from the base-line 

 which would be yielded on a curve ; but the base-line of a gibbous-sided 

 species like A. woodwardi is much shorter than would be a base-Una 

 measured over the gibbous curve. Therefore a base-line of 26 mm. in 

 A. tutcheri is relatively longer than is a base-line of 26 rnm. in A. wood- 

 wardi. Therefore the proportions of the lobes in A. tutcheri, since they 

 are reckoned in regard to a relatively longer base-Une, would come out 

 shorter than those of A. woodwardi. 



These figures of sutural proportions are a good illustration of their 

 reliability in the detection of generic affinity. They show, also, how 

 dangerous it is to assign a species to a given genus without taking note 

 of its suture-line. The eye alone is not to be trusted — compass-measure- 

 ment is essential. 



Nomen nudum : This term is used sometimes quite incorrectly. 

 Mr. C. H. Crickmay speaks (Proc. California Acad. Sci., (4) xiv (3), 1925, 

 p. 77) of " a vast assemblage of nomina nuda — chiefly names applied 

 with no, or with incomplete, description by Alpheus Hyatt." Dr. L. F. 

 Spath (Yorksh. Amm. ; Naturalist, 1925, 359, footnote i) remarks 

 " Simpson's names must be considered to be nomina nuda as much as 

 Hyatt's unfigured Liassic species recently referred to by Crickmay." 

 Dr. Spath's dictum is wholly incorrect so far as Simpson's names are 

 concerned, and Mr. Crickmay's is mainly wrong. Only those names 

 can be called nude which have no covering description of any kind. 

 So long as a name has a covering description, however insufficient it 

 may be, the name cannot be called naked. The covering description 

 may be as exiguous as the fig-leaf aprons credited to Adam and Eve, 

 or as the bathing-drawers which were considered right in the days of 

 my early manhood, but are condemned by the present decadent age ; 

 yet so long as there is a covering, there is not nudity. Hyatt's and 

 Simpson's names, when covered by any description, are not nomina nuda, 

 any more than are the names of Linne, Bruguiere and others. In 

 natural history a description alone is sufficient to establish priority in 

 the naming of a species. Ammonite workers are not a law to them- 

 selves : they must conform to the laws of natural history nomenclature. 

 Insufficiency of description cannot be urged as ground for the rejection 

 of a name — insufficiency is a relative term, and would lead to endless 

 argument. It might be urged that no description is ever sufficient. 



Of course, figures are desirable. It was to supply the lack of figures 

 which obtained so widely in regard to Yorkshire Ammonites, and were 

 really a stumbling block in the way of their proper study, that this 

 work was commenced. It can, at least, claim to have been successful 

 in figuring a large number of species, which before were only known 

 from descriptions. It can claim to have placed the majority of Yorkshire 



