REPORT ON THE ECHINOIDEA. 191 



fasciole in Aceste is strikingly like that of the peripetalous fascicle of Schizaster, and it is 

 indeed difficult in this genus to know whether to call it a peripetalous or an internal fasciole. 

 Taken in connection with the course of the fasciole of Aet'oj^e and of Gualteria, in which 

 we find the lateral ambulacra with double pores are not in the least modified within the 

 fasciole, we cannot resist the conclusion that the internal fasciole is after all only a modi- 

 fication of the peripetalous fasciole ; what has been called an internal fasciole is in reality 

 only an embryonic peripetalous fasciole. If we compare the internal fasciole of Echino- 

 cardium with the peripetalous fasciole of a young Brissojisis, we shall find that it encloses 

 mainly the abactinal region of the odd ambulacral petal, and, extending only slightly 

 beyond the apical system, encloses only one or two pairs at the outside of the ambulacral 

 pores of the other ambulacra, and that it is not only with increasing age that the posterior 

 part of the fasciole extends further down on the sides of the test so as eventually to 

 enclose the whole of the petaloid portion of the ambulacra (the abactinal portion). In 

 Echinocardium and other genera in which the peripetalous fasciole always remains 

 internal, it merely does not enclose the whole of the petaloid part of the ambulacra, and 

 the posterior part of the fasciole remains always in close proximity to the apical system ; 

 the same is also the case in Breynia and Lovenia. In the former genus there is, however, 

 in addition what has always been called a peripetalous fasciole. I am inclined to look 

 upon this fasciole as a modified lateral fasciole, which takes its origin from the odd 

 anterior ambulacral region instead of starting, as is the case in Schizaster and other 

 genera, from the peripetalous fasciole in the posterior interambulacral species. I am 

 led to take this view from a comparison of the genera in which this so-called internal 

 fasciole exists for the following reasons : — 



We find in Lovenia that the anterior extremity of the fasciole where it crosses the 

 ambulacral region is nearly lost in the midst of the minute miliaries which cover the 

 whole of the shallow anterior groove, and which it is difficult to distinguish from the 

 miliaries of the fasciole, the whole anterior groove becoming, as it were, a broad fasciole 

 from which the peripetalous fasciole of Breynia, where we find the same structural 

 features, takes its origin, and to all aj)pearances looks like a peripetalous fasciole, but is 

 in reality, as is shown l^y Lovenia, a lateral fasciole, taking its origin from the anterior inter- 

 ambulacral region. In Lovenia this lateral fasciole has more the character of a marginal 

 fasciole, extending but little beyond the anterior pair of ambulacral petals. This rudi- 

 mentary fasciole in Lovenia is interesting as showing how easily it may be for closely 

 allied genera to have what may seem a marginal fasciole, formed by the concentration at 

 the ambitus of the miliary tubercles, especially if flanked above and below by coarser 

 tubercles ; in fact, the whole anterior part of the test of Lovenia may be said to a certain 

 extent to be covered by a gigantic fasciole, highly specialised in a part of the test to form 

 an internal fasciole, and a short rudimentary marginal or lateral fasciole extending a short 

 distance along the ambitus ; while in Breyi.ia the structure of the anterior part of the test 



