H 
ECHINOID FROM THE CRETACEOUS OF BRITISH COLOMBIA 
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Tuberculation is relatively coarse on the aboral surface, with 
;cattered primary tubercles (crenulate and perforate) up to 0.6 mm 
liameter set amongst a fine granulation of miliary tuberculation 
Fig. 5B). A well-developed peripetalous fasciole, with up to 12 
ines of densely spaced (hexagonally packed) miliary tubercles, is 
leveloped around at least the posterior of the test. It runs immedi- 
tely beneath the ends of the petals and is indented in the 
osterio-lateral interambulacra. Unfortunately, most specimens are 
reserved as internal moulds so it is impossible to tell whether the 
asciole continues around the anterior of the test. It is also impossible 
0 tell whether there was a subanal fasciole present. 
Some specimens have scattered primary spines preserved flat- 
ened against the test surface. 
XEMARKS. The new species is placed in the genus Plesiaster on 
ccount of its peripetalous fasciole and petaloid anterior ambulacrum. 
nly a few spatangoid genera have petaloid anterior ambulacra, 
amely Douvillaster Lambert, 1917, Plesiaster Pomel 1883, Hetero- 
ampas Cotteau 1862, Isomicraster Lambert 1901 and Barnumia 
105 
\s 3. Camera lucida drawings of Plesiaster vancouverensis sp. nov. uppermost Santonian; Lower Campanian, / (S.) schmidti Zone, French Creek, 
Vancouver Island, British Columbia. A, BMNH EE5078; B, BMNH EE5083; C, BMNH EE5076, D, BMNH EE5079: E, BMNH EE5081. 
Cooke 1953. Neither Douvillaster nor Isomicraster have fascioles 
and thus differ significantly from the Canadian species. Barnumia 
can also be dismissed from consideration since its fasciole is not 
peripetalous but lateral, extending around the ambitus and well- 
separated from the base of the petals. The type species of 
Heterolampas, H.maresi Cotteau, has a narrow but continuous 
peripetalous fasciole and petaloid ambulacra. However, it differs 
significantly from the Canadian species in its labral and apical disc 
structure. The apical disc of H. maresi, though ethmophract, is 
composed of an enlarged madreporite plate which occupies the 
centre of the disc and separates the posterior two genital plates. Its 
labral plate is large and broadly triangular, firmly abutting both 
sternal plates. Finally, the peristome of H. maresi lies considerably 
further back from the anterior than that of the new species. 
Plesiaster Pomel, 1883, was established for Micraster-like forms 
with a partial peripetalous fasciole developed at the base of the 
petals. Zhagbib-Turki (1987) has given a recent analyses of the 
North African species and concluded that Plesiaster should be 
placed in synonymy with Micraster. However, the differentiation of 
