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IOWA ACADEMY OP SCIENCES. 
practically nothing except the general outlines. The fact that 
the plates appear to be somewhat beveled for over-lapping 
seems to be the chief reason for referring the form to McCoy’s 
genus Perischodomus, but this feature is also known among 
some of the species Archseocidaris. 
Lepidechinus rartspinus Hall. 
Lejyidechinus rapsxnniis Hall, 1867; N. Y. State Cab. Nat. Hist., 
20th Ann. Rep., p. 295, pi. ix. fig. 10. 
Test spherical or depressed spheroidal. Interambulacra 
with seven to nine ranges of plates, which are imbricated from 
below upward and from the middle of the areas outward; each 
plate with large central boss. Ambulacra narrow, with a 
double range of small low plates, each of which is pierced by 
tw'o pores near the distal extremity; thiee to four plates in the 
space of one-tenth of an inch. 
Horhon andloQcdiiles. Devonian, Chemung sandstone:- Mead- 
ville. Pa.; Carbc nlferous, Waverly sandstone: Licking county, 
Ohio. (Hall.) 
Lepidechinus imbricates Hall. 
LepidecJnmis imdric^^^ Hall, 1861; Desc. New Species Crinoidea, 
Prelim. Notice, p. 18. 
Horizon and localities. Lower Carboniferous, Burlington lime- 
stone: Burlington, Iowa. 
The original description of this form is too defective to merit 
recognition and it is difficult to determine exactly what its dis- 
tinctive characters are. From the location and the collection in 
which it was probably seen the type was presumably very nearly 
related to that figured by Meek and Worthen as Le'pidocidaris 
squamosus. The fact that Hall subsequently described and 
figured another species wffiich he referred to Lepidechinus 
(A. rarispinus) gives grounds for considering the genus which 
w^ould otherwise have to be ignored entirely, for the illustration 
shows clearly what type he had in mind when he first proposed 
the name. Taking this view of the data presented Hall’s genus 
should be regarded as valid. 
Meek & Worthen’s name, Lepidocidaris, wffiich was proposed 
several years ago, after Hall’s genus, does not appear to be suf- 
ficiently distinct to deserve separation; and it is not improbable 
that the type of the two genera proposed are one and the same 
species. Doubtless the last mentioned authors were somewhat 
misled by the brief diagnosis of the former author. 
