PEAT Ei. 
a. Anus. ov. Ovary. 
br. Gill. pe. Polar cell? 
dp. Deutoplasm. st. Stomach. 
ep. Epiblast. vm. Egg membrane. 
gen. Genital cells. a. Adduetor muscle of the shell. 
gym. Gastrula mouth. B. Antennary muscle. 
h. Heart. y- Shell gland. 
hy. Hypoblast. 6. Muscular impression. 
i. Intestine. G Chitinous support of the caudal fork. 
1. Liver. (2 Threads (nervous ?) connected with the sete of the shell. 
76. Labrum. n- Cephalic plate. 
m. Mouth. 3. Maxillary somite. 
ms. Mesoblast. u Rudiment of sensory seta. 
mt. Metastoma. Ke Shell. 
n’. Primary brain. A. Dorsal organ. 
~ mn. Secondary brain. Me Inner membrane of fold over the eye. 
oc. Compound eye. ¥. Seta. 
ocl. Simple eye. wr Olfactory seta. 
oes. (sophagus. &. Caudal fork. 
The Roman numerals denote the appendages of the body in their consecutive order. 
1-12. Development of Ostracopa (Cypris). Figures from Cart Criaus, Beitrage zur Kenntniss 
iP Y} J Ss 
~ 
10 
pte 
12. 
13 - 
der Ostracoden. I. Entwickelungsgeschichte von Cypris. Schriften Gesellsch. Beford. 
gesammt. Naturwissensch. Marburg, IX., Taf. L, IL, 1868. 
. First larval (nauplius) stage of Cypris ovum. Differs from the typical nauplius form in having a bivalve 
shell, and in the second and third pairs of appendages not being biramous. a, adductor muscle of the 
shell. 8, antennary muscle. s?, stomach. 7, intestine. 
. Third appendage of the same stage, locomotive in function. At its base is seen the rudiment of the future 
mandible. The appendage terminates in a hooklike seta. 
. Second stage of Cypris fasciata. Two new pairs of appendages have appeared, viz. the first pair of maxille (IV) 
and the first pair of feet (VI). The fifth pair of appendages (second maxillw, ‘‘maxillipeds” of some 
authors) are not developed till later. The first pair of feet (VI) bear a terminal claw for adhering. The 
masticatory part of the mandible (IIT) is well developed. III’, mandibular palpus. m¢, metastoma. 
. Third stage of Cypris fasciata. V, rudiment of second maxilla. The first maxilla (IV) has acquired its large 
setose appendage (IV’). 
. Fourth stage of Cypris fasciata. 
. Fifth stage of the same. The second maxille (V) have developed into ambulatory appendages, terminated by 
a hook similar to that borne during the previous stages by the sixth pair of appendages. The latter have 
lost their hook. +, shell gland. J, liver. 6, muscular impression on the shell. 
- Second maxilla (V), first foot (V1), and caudal fork (&) of the same stage. 
. Sixth stage of the same. All the appendages of the adult are now present, the second pair of feet (VII) having 
appeared. The second maxille (V) are beginning to lose their ambulatory function, and become converted 
into masticatory organs through the enlargement of their cutting blades and reduction of the palp. The 
hook at the end of these appendages has disappeared, and one reappears at the end of the first pair of 
feet (VI). &, abdomen or caudal fork. , chitinous support of the caudal fork. 
. First foot of the same, sixth stage. 
Caudal fork of the same, sixth stage. 
Seventh stage of the same. All the appendages have practically acquired their permanent form. J, first 
antenna. II, second antenna. II’, basal segment of second antenna. III, mandible with four-jointed pal- 
pus. 1V, first maxilla with gill-plate. V, second maxilla with jaw-process and leg-like palpus. At the 
base of the latter there is a small gill-plate, not seen in the figure. VI, first leg. VII, second leg. 
Both pairs of legs are now jointed. ov, rudiment of the ovary. 
Adult female of the same. ¢ network composed of groups of cells from which fine threads proceed to the 
sete of the cuticle. 
The marine genera of Ostracoda have an abbreviated metamorphosis. 
13-24. Development of Cravocers. Figures from Cart GRoBBEN and G. O. Sars. 
22. Development of the summer egg of Moina rectirostris. From Grobben, Die Entwickelungsgeschichte der 
Moina rectirostris. Arbeiten Zoolog. Inst. Univ. Wien, II., Taf. XI.-— XIV., 1879. 
The summer egys are parthenogenetically developed within the brood-cavity of the parent. 
