88 Reports and Proceedings— 
mens of Hugeniacrinus from Streitberg. The species of Hugenia- 
erinus, Phyllocrinus, and Trigonocrinus may be arranged in a series 
which is apparently one of evolution. The present genus is, there- 
fore, to be placed with the Hugeniacrinide, although its characters 
are not those of the family as heretofore defined. This is seen from 
the following diagnosis :— 
Trigonocrinus, gen. nov.—Calyx roughly triangular or trilobate 
in section. Basals 4, but one so atrophied as to be almost invisible ; 
all fused into a basal ring. First radials 4; the two on either side 
of the smallest basal half the size of the others, thus maintaining 
the triangular symmetry; all closely united, with each suture-line 
in a groove. Processes of radials well developed, forming spines 
homologous with the petals of Phyllocrinus; excepting the adjacent 
processes of the smaller radials, which only form a minute ridge. 
Articular surface of radials curved gently inwards and upwards; 
muscular impressions indistinct or absent; no articular ridge; no 
canal-aperture. Arms unknown; ? represented by fleshy appen- 
dages. Calycal cavity contained in first radials; with small round 
ventral aperture, surrounded by a rim, which is the only relic of a 
muscular attachment. Stem unknown. 
The two calyces belong to the same species, viz. T. liratus, sp. 
nov.—Calyx rather more elongate than in the known species of 
Phyllocrinus; basals ornamented with minute granules; radials 
ornamented with similar granules run into curved ridges, which, 
owing to their differing intensity, give an imbricated appearance ; 
spines triangular in section, with the base of the triangle directed 
inwards, the apex outwards, the angles often rounded. 
The differentiation of Trigonocrinus from the central Eugeniacrinid 
type has been effected on the one hand in accordance with the 
principles of “ Degeneration,” ‘‘ Reversion,” and ‘‘ Use and Disuse”’ ; 
while, on the other hand, it exemplifies certain methods of change 
in organic forms, which may be referred to the categories of (1) Sport, 
(2) Hypertrophy and Atrophy, (3) Fusion and Fission. Thus con- 
sidered it is of unique interest among Crinoidea. An examination of 
the variations in symmetry presented by the Echinodermata suggests 
the conclusion that the Pentamerous type was originally evolved 
from another system, or at least that it was selected from among 
other variations, that it has survived, and that it has been kept true, 
as being the fittest. 
Appendix I. Sudden deviations from normal symmetry in Neo- 
crinoidea. 
A collection of instances from previous authors, with a few addi- 
tions, the whole illustrating the latter portion of the paper. 
Appendix II. On Marsupites testudinarius, von Schlotheim, sp. 
A synonymy of the genus Marsupites; it contains but one known 
species, and all other names must yield to this one. 
2. “On Archeocyathus, Billings, and on other Genera allied 
thereto, or associated therewith, from the Cambrian Strata of North 
aoe Spain, Sardinia, and Scotland.” By Dr. G. J. Hinde, 
