LOWER CRETACEOUS FOSSILS — ETHERIDoi:. 141 



talented man did not live to elaborate the classification there 

 forecast. Hyatt distributed the evolute Cephalopoda through 

 several families, but those with which we are at present chiefly 

 concerned are the following : — 



1. AncyloceratkUr — " Includes only such forms usually assigned to Anry- 

 loceras, Crioceras, etc., as have three rows of tubercles on either side on 

 the larger costre. Between the latter are smaller costations without 

 tubercles. Costaj sometimes interrupted across the venter by a smooth 

 zone." Figures A. matheronianum, D'Orb. 



2. Grioceratida; — " . . . with only two lines of tubercles on either 

 side of the median line of the venter. The latter may have a smooth zone 

 or be crossed by the coske, which are either single or double between the 

 tubercles " 



3. Anisoceratidce — " .... two rows of tubercles on either side the 

 median line of the venter. Cost;t- large and single, or imperfectly bifurcate, 

 and may cross the venter." 



4. Hamitidce — Single costaj crossing the venter uninterruptedly, and no 



tubercles at any stage. 



It appears tome that Hyatt attached considerable classificatory 

 value to the external sculpture, and had he lived to complete his 

 work a path very difficult to others would have been rendered 

 smoother. 



IV. — Australian Crioceri. 



There is a strong community of structure throughout all the 

 Australian shells of this type. It is only by attention to the 

 degree of inrolment, breadth of the venter, convexity of the Hanks 

 and the sculpture, that specific separation and demarcation can 

 be attained ; I have paid attention, as a primary means, to the 

 sculpture of the initial whorls, in the few instances in which it is 

 visible. Nearly all our forms appertain to the more closely 

 coiled type ; apparently only two show any tendency to the open 

 coil condition. I do not give detailed descriptions of the sutures. 

 The specific differences appear to be so trivial that short of a 

 special terminology for the lobe and saddle subdivisions it is 

 impossible to express oneself clearly and at the 'same time tersely. 

 Suffice it to say that throughout the species the community of 

 structure in this respect is remarkable. In this they appear to 

 be in accord with those forms studied by Messrs. Sarasin and 

 Schondelmayer. The septa, speaking generally, throughout our 

 specimens, are divided into six principal lobes as in the typical 

 Hoplite-like Crioceri, such as C. emerici, C . matheronianum, etc.; 

 the superior lateral lobes are always the longest with a broad 

 body. 



The descriptions that follow 7 cannot be regarded as eminently 

 satisfactory, nor do I see how such can be the case when the 



