A. R. Horwood—Upper Trias, Leicestershire. 417 
the bone-bed, associated with fish. As Harrison found his specimens 
with fish also it is probable that this is the same bed, and the small 
form is no doubt referred to. 
I was myself at first inclined to consider there were two species, but 
more material being forthcoming I came to the conclusion that the 
speciesis dimorphic. It may be noted that the large form appears first, 
the small one later. In this case the small one may be regarded as 
degenerate, as Mr. Cannon has suggested to me. ‘The opinion I hold 
is shared by Mr. W. K. Spencer, to whom they were submitted by 
Dr. Bather, whose advice I had sought upon this point. Dr. Bather, 
like myself, was inclined to consider the forms distinct, but concurs 
with my later view, borne out by Mr. Spencer. It is sufficient to 
remark, at this point, that if the large form is more specialized than 
the small one, the line of degeneration here is connected with 
a reduction in the length of the arms, and a relative increase in their 
width at the base, causing a corresponding decrease in the width of 
the interbrachial areas. Some other differences are correlated with 
this. But as it is proposed to publish a separate account of these 
forms, figures of both are merely given here to show the dimorphism 
of this species (see Pl. XVII, Figs. 8, 4). Wright’s description and 
figure being in some respects incomplete it will therefore be necessary 
to amend them. Since the material is not easy to study from the 
pyritized nature of the matrix, it is hoped further material will throw 
some light upon obscure points. 
“* Echinus”’ (? Pseudodiadema). Browne mentions that Mr. A. EH. 
Baker found a fragment of an Hchinus test at Spinney Hills. 
_ Echinoderm ossicles. \ Barrow Hill. 
Piscus.'— Hybodus cloacinus, Quenst. (teeth and dorsal fin-spines). 
1. Spinney Hills. 2. Haddon Street, Crown Hills. 
Hybodus minor, Ag. (teeth). 1. Spinney Hills, Glen Parva. 
2. Kast Leake. These are founded on teeth, and the dorsal fin- 
spines termed WVemacanthus monilifer are probably referable to the same 
species as well as, perhaps, Sphenonchus. 
Nemacanthus monilifer, Ag. (dorsal fin-spines). 1. Spinney Hills, 
Glen Parva. 2. East Leake. 
Sphenonchus (cephalic spine). 1. Spinney Hills. 
Acrodus minimus, Ag. (teeth and spines). 1. Spinney Hills. 
2. Haddon Street, Glen Parva, East Leake, Barrow. 
Ceratodus latissimus, Ag. (teeth). 1. Spinney Hills. 1. Glen 
Parva (?). 
Gyrolepis albertii, Ag. (scales). 1. Spinney Hills, Glen Parva, 
Barrow. 2. Haddon Street, Kast Leake, Glen Parva. 
Gyrolepis quenstedti, Dames (scales). 2. Hast Leake. 
Colobodus maximus, Quenst. (teeth and scales). (= Sargodon 
tomicus, Phén.) 1. Spinney Hills. 
Colobodus sp. 1. Haddon Street (scales), Glen Parva. 
Sargodon sp. ?1. Barrow Hill. 
1 See Dr. A. S. Woodward, Trans. Leic. Lit. and Phil. Soc., 1889, p. 18 
et seqq. 
DECADE VI.—VOL. III.—NO. Ix. 27 
