RESUME. 141 



The branches A, B, C of the family Hildoceratidce seem to be fairly well 

 characterised ; but I intend, in the text and plates, to place between the second and 

 third branches a series of species, which appear to combine in themselves certain 

 of the characters of all three branches in union with their own especial features. 

 I refer to the genus Haugia. By courtesy, I propose to include it in the Hildo- 

 ceratidse, but it cannot apparently be placed in either of the divisions A, B, C, nor 

 does it come in the order of descent into any of these branches. 1 So far as its 

 characters are concerned it apparently connects A and B with C, and has the 

 ribbing of Lillia with a suture-line between Harpoceras and Grammoceras ; and so I 

 have, for better comparison, placed it here instead of at the end of the Hildoceratidae. 

 Concerning its descent, I cannot speak definitely, nor can I trace the steps by 

 which it has arrived at its present development. In breadth and compression of 

 whorl and absence of furrows it shows high development ; in involution it is in a 

 transitional state, and also in the matter of its ribbing ; its sutures show 

 development in the lateral lobes, but not in the size or number of the 

 auxiliaries. One character it has carried to great perfection, namely, the 

 large hollow-carina. In this it certainly distances all rivals — the genus 

 Harpoceras being the only one which at all approaches it. 



1 Unless it be a descendant of the earliest forms of Lillia. If so the changes must have taken 

 place very rapidly ; it will, also, in that case, be but little out of its right order. 



