86 



does not divide into lobes, as in Brachiolites : there is simply, in 

 order to ensure the greater security of the whole polypiferous 

 surface, an occasional constriction of the head and narrowing of 

 the plaits attached to it ; which plaits expand again, like an open 

 fan, in the following compartment. 



The appearance of the plaits themselves is very remarkable. 

 Their frequent constrictions give them a puckered or zigzag ap- 

 pearance, so that a vertical section F ; g L 

 has a figure of this kind. This 

 figure shows, also, how the pro- 

 jecting points of the plaits are 

 often attached, for security, to 

 the head. When the body is broken away the cast left is very 

 curious, the matrix being always broken off in many of the places 

 where it has filled a pucker in the upper plait, depressed where 

 there was a pucker in the lower plait. This is seen on the right 

 hand of fig. 1. PI. XV. 



The species rarely attained half an inch in height or an inch 

 in breadth, though specimens often extend between two and 

 three inches in length. 



It seems to me that the cephalic constrictions most probably 

 mark periods of growth *. They vary in number much in dif- 

 ferent specimens, and, as has been seen, are sometimes not found 

 at all, in which case there are several openings in the undivided 

 head. 



Specimens sometimes assume irregular forms, as if, after 

 death, the long body had become twisted, which I have little 

 doubt was, in many such cases, the real fact. 



I have placed this species next in order to C. campanulatus, 

 inasmuch as, on the one hand, the mode of attachment of the 

 cephalic membrane to the plaits resembles very much that which 

 is found in C. campanulatus, while, on the other hand, the fact of 

 the openings in the head of this species being generally several 

 instead of only one, places it in some relation to the species which 

 will next claim attention. 



4. Cephalites perforatus. PI. XV. fig. 2. 



Plaits wide and very deep, so as to leave no distinct and single 

 central cavity ; dividing, and so reduplicating, very constantly, 

 longitudinally, but not transversely ; somewhat winding both 

 longitudinally and laterally ; occasional points of anastomosis 

 near the outer surface : head covering the entire top and round- 



* Specimens, apparently entire, are sometimes found, Raving one only 

 of the rounded divisions, and thus bearing some resemblance to a very small 

 f. campanula fas, with its root at one end instead of at the base. 



