146 CALIFORNIA ACADEMY OF SCIENCES. 
bed of the river south of town at a water-hole in the otherwise dry creek bottom 
sand. It occurred here with Deltania and Limnodrilus. The sand was merely moist 
on account of overlying rubbish and sacks. The species is undoubtedly a native one 
and the only Acanthodrilid found on the coast so far north in the open ground, and 
and on this account even of geographical interest. The intestine of the worm was 
gorged with the coarse white sand of the river bed. The anterior part of the worm 
was cut lengthwise, one-half dissected and the other half sectioned crosswise. The 
want of specimens made a full investigation impossible, though I believe none of the 
important points remains in doubt. I have no reason to believe the species is scarce, 
though probably it issharing the fate with all native worms, that of being displaced by 
European importations. The species is dedicated to Professor W.S. Keyes, my com- 
panion in many travels in tropical Mexico. 
Affinities. It is interesting to note that Aleodrilus shows considerable affinity 
to the only other North American genus of this family, viz.: Diplocardia. It re- 
sembled this genus by having two gizzards, no calciferous glands, meganephridia, no 
sacs with penial sete. It resembles Benhamia in having two gizzards, ete., but it 
differs from these two, as well as from all other Acanthodrilide, by the far backward 
position of the prostate and spermiducal pores, these being in xx, xxi and xxii re- 
spectively, while all other genera of this family have these respective pores in xvii, 
xviii and xix. The genital male pores are thus in Aleodrilus pushed three somites 
further back. Considering these and some minor characters I believe I am_ justified 
in placing this worm in a new genus. 
Aleodrilus Keyesi n. sp. 
Derrinition. Length 7 em., by 5 mm. wide; number of somites 80. First dor- 
sal pore vitirix, Clitellum complete in anterior, incomplete in the posterior somites, 
brititxx. No penial sacs and sete. Common sete paired, those of the inner couple 
closer than those of the outer couple. Spermathecal pores between vit/oiii and viti/ix. 
Gizzards inv and vi. No caleiferous glands. Nephridia not covered by a cwlomic man- 
tle. Nephropores outside of sete 4. Hearts in x, wi, avi. Sperm-sacs racemose in x, 
vi, vii. Testes ina, vi. Color pale flesh, no pigment. Habitat, Northern Baja Cal- 
ifornia, at Ensenada de Todos Santos. 
EXTERNAL CHARACTERS. 
Color is very pale, mottled and marbled, showing clearly the intestines and 
blood vessels. When collected this worm resembled in delicacy of color and trans- 
parency Deltania elegans and I supposed it to be this species. Spermathecal pores are 
separate in front of setee 1 and 2 between vii/viii and vili/ix. Setw are ventral and 
lateral, 8 in each somite approached in couples. The sete of the inner couple is 
closer than those of the outer couple. The distance between the couples is about twice 
as large as the distance between sete 1 and 2, and one and one-half us wide as the dis- 
tance between sete 3 and 4. No penial sete in special sacs. All setee are sigmoid 
without sculpture. The anterior five somites are two-ringed, that is with a single 
groove in the equatorial region, while all the following somites are four-ringed, or 
