46 MAZATLAN BIVALVES 
same colour, lunular purple ray on one valve only.—145, 9 sp. 
same colour, purple rays absent.—146, 10 sp. and 2 valves, 
pale yellow: this is the most frequent state.—147, 8 sp. 
white, normal shape.—148, 8 sp. white, transverse.— 149, 12 
sp. white and pale yellow, with irregular pale violet concen- 
tric bands.—150, 5 sp. orange yellow, similarly banded.— 
151, 5 sp. stained with purple and green.—152, 15 sp. yellow. 
green at umbos and posterior slope.—153, 15 sp. whitish, band- 
ed with violet, green at posterior slope.—154, 9 sp. plain yellow 
with greenish slope.—155, 9 sp. white with greenish slope.— 
156, 7 sp. orange yellow stained with purple.—157, 2 sp. and 
l valve, do, highly coloured, form approaching D. Conradi.— 
158, 6 sp. with broad brown rays.—159, 6 sp. with very faint 
rays.—160, 5 sp. shewing distorted growth. 
Besides these were found a few scores of specimens which, 
when examining D. punctatostriatus I have generally turned 
over to D. Conradi; when examining the latter, have been dis- 
posed to turn back again. They are here grouped according to 
the preponderance of characters.—Tablet 161 contains D. punc- 
tatostriatus approaching D. Conradi, 4 sp. whitish.—162, 6 sp. 
yellow.—163, 3 sp. rayed.—164, 2 sp. yellow, transverse.—165, 
3sp. reddish, transverse.—166, 3 sp. whitish, narrow margin. 
167; 3. sp. very gibbous.—In all 192 shells, the result of very 
frequent elimination from an examination of many thousand 
specimens ; no two probably being exactly alike. 
75 (6.) Donax P PUNCTATOSTRIATUS, var. CHELATUS. 
D. ?punctatostriatus, t. maxime inequilaterali, margine ven- 
trali vix angulato: superficie posticd dense liratad, liris ex- 
pressis radiantibus : interstitiis dense decussatis, lineolis valde 
impressis : sculpturd partem versus anteriorem, im lineas punc- 
tarum mutante, punctis angulatis : margine plerumque simplici, 
epidermide densa rugosa tecto. 
Nearly 40 specimens have occurred, agreeing in the above 
characters, while only 2 shewed the least disposition to depart 
towards the ordinary type. Shape extremely inequilateral, 
anterior end much prolonged. Sculpture deeply marked on 
the posterior and posterior ventral part ; with elevated ridges, 
and the furrows not simple rows of dots as in D- punctato-stria- 
tus," but with short lines impressed as with a file-cutter’s tool. 
These gradually subside anteriorly into punctate striation, but 
even then the dots are angulated, not round. ‘There is a large 
