1883.] Heterogenetic Development in Diaptomus. 503 
SIMOCEPHALUS DAPHNOIDES, sp. nov. (Figs. 30, 31, Plate V; Fig. 
io, Plate VI. - 
Four nominal speeies of Simocephalus are deseribed: S. vetu- 
lus Müller, S. expinosus Koch, S. serrulatus Koch, S. americanus 
Birge. The differences in some cases seem quite trivial, since the 
form of the macula nigra certainly varies with age along with the 
shape and armature of head and the general shape of the body. 
However, the present species is so unmistakable that it is not 
requisite to enter upoa a discussion which lack of material 
makes undesirable. , 
Simocephalus daphnoides, sp. nov.—General shape very like Daphnia; head regu- 
curved and not strongly angled in front, not marked off from the body by a strong 
depression ; eye of moderate size, macula nigra oval to rhomboidal; antennules long 
curved; anterior portion of shell as deep as the posterior; the three curved 
Spines at the lower posterior angle of shell are wanting; abdomen much as in S. 
vetulus > claw fringed part way with weak spines. 
This species is recognized by its oval shape and the Daphnia- 
like shape of head. In old females the spine is about midway of 
| the depth of the shell, but the upper outline is regularly curved 
and not keeled as in vetwlus (Fig. 29, Plate V). Quite charac- 
teristic is the absence of the three or four curved spines on the 
shell angle (comp. Fig. 31 with 292). On the whole in this spe- 
‘ = an approach to Daphnia may be seen. Near Decatur, Ala., 
= with Scapholeberis angulata, also in all Southern Alabama. 
Certoparunta ALABAMENSIS, sp. nov. (Figs. 11-12. Plate VI). 
Ceriodaphnia is a very perplexing genus, and one in which the 
Ka ad age has not been studied. Three species have been 
F oned from America, C. cristata Birge, C. consors Birge, and 
3 m e i ata (= dentata Birge), there remaining pulchella, rotunda, 
®© Kata, laticauda (? ) and quadrangulata, as described in Europe. . 
e oe typical C. reticulata were collected back of Paducah, Ky. 
EA Pepe shape of the fornices figured by P. E. Mueller can 
same oed by pressure. I have little doubt that this is the 
en described from Massachusetts and Wisconsin by 
ieai head is not so suddenly angled behind the eye as 
Cc by Birge, but more so than represented by Mueller. 
Offered; StS, sp. nov. — The form for which this name is 
but it Sa known from a single gathering at Tuscaloosa, Ala., 
Nts from any known species so much as to leave no 
Ps, 
a 
