24 University of Michigan 
Simpson have followed him. However, catillus Con. differs 
from coccineus Con. (figured on the same plate) by the greater 
obesity of the shell, and this is exactly the character by which 
U. solidus Lea differs from coccineus. Thus, catillus clearly 
is the same as solidus, having priority over it. 
Utterback was the first to recognize this, but his treatment 
of this group (introducing, besides Pl. (obl.) catillus, another 
species called Pl. catillus Con. solidus Lea) is contrary to 
all nomenclatorial rules. According to Ortmann, all these 
forms are variations or varieties of Pl. cordatum (Raf.). 
PLEUROBEMA COCCINEUM PAUPERCULUM (Simpson), 1900 
Type locality: Niagara Falls. 
Quadrula coccinea paupercula Simpson, co’, p. 789 (not Unio pau- 
perculus (Lea) ’61) = Quadrula paupercula (Lea), Simpson, ’14, p: 862. 
Quadrula coccinea magnalacustris Simpson, 714, p. 884.. 
Simpson’s Quadrula coccinea paupercula is not a homonym 
of Unio pauperculus Lea, the original form of the name of 
Lea’s species. It is a forbidden name as long as the two 
forms are placed in the same genus. If they are placed in 
different genera, as Quadrula paupercula (Lea) and Pleuro- 
bema coccimeum pauperculum (Simpson), the name pauper- 
culus is valid in each case. 
PLEUROBEMA PYRAMIDATUM (Lea), 1831 
Type locality: Ohio. 
Obliquaria rubra Rafinesque, ’20, p. 314 (standing under genus 
Amblema. 
Pleurobema mytiloides Rafinesque, ’20, p. 313, pl. 82, f. 8, 9, 10. 
Unio pyramidatus Lea, ’31 (not ’34 as given by Simpson), p. 109, 
Pls, 1. 30: 
U. triangularis Raf.=U. lateralis Raf.=U. sintoxta Raf.= U. 
mytiloides Raf. =U. rubra Raf.=U. pyramidatus Lea, Conrad, ’34, 
Dp: 72 
U. mytiloides Raf. =U. rubra Raf.=U. pyramidatus Vea, Ferus- 
Sac, “35, p: 267 Conrad, °36, ‘p. “41, "pl. 20: 
