The Roman numerals denote the appendages of the body in their consecutive order. 



1-12. Development of ()str.\coda {Ci/pris}. Figures from Cabl Claus, Beitrage zur Kenntniss 

 del- Ostracoden. I. Eiitwickelutigsgeschichte von C'l/prk. Schrifteu Gesellsch. Befcird, 

 gesamnit. Naturwisseusch. Marburg, IX., Taf. I., II., 1868. 



1. First larval (nauplius) stage of Cijpris ovum. Differs from the tyiiical nauplius form in having a bivalve 



shell, and in the second and third pairs of appendages not being biianious. a, adductor muscle of the 

 shell. /3, antenuary muscle, st, stomach, i, intestine. 



2. 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. 



3. Second stage of Cyprif fasciata. Two new pairs of appendages have appeared, viz. the fii-st pair of ma.xilke (IV) 



and the first pair of feet (VI). The fifth pair of appendages (second nia.xillie, " inaxillijieds " 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 (III) is well developed. Ill', mandibular palpus, m t, metastoma. 



4. Third stage of Cijpris fasciata. V, rudiment of second maxilla. The first maxilla (IV) has acquired its large 



setose appendage (IV). 



5. Fourth stage of C'ypris fasciata. 



6. Fifth stage of the same. The second maxillne (V) have developed into ambulatory appendages, terminated by 



a hook similar to that borne during the previous stages by the sbcth pair of appendages. The latter have 

 lost their hook, y, shell gland. I, liver. S, muscular impression on the shell. 



7. Second maxilla (V), first foot (VI), and candal fork ({) of the same stage. 



8. Sixth stage of the same. All the appendages of the adult are now present, the second pair of feet (VII) having 



appeared. The second maxilla; (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). I, abdomen or caudal fork, c, chitinous support of the caudal fork. 



9. First foot of the same, sixth stage. 

 10 Caudal fork of the same, sixth stage. 



11. Seventh stage of the same. All the appendages have practically acqnired their permanent form. I, first 



antenna. II, second antenna. 11', basal segment of second antenna. Ill, mandible with four-jointed pal- 

 pus. IV, 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, o v, rudiment of the ovary. 



12. Adult female of the same. (, network composed of groups of cells from which fine threads proceed to the 



seta; of the cuticle. 

 The marine genera of Ostracoda have an abbreviated metamorphosis. 



13-24. Development o/ Cladocera. Figures from Carl Grobben micI G. 0. Sars. 



13 - 22. Development of the summer egg of Afoina rectirostris. From Grobben, Die Entwickelungsgeschichte der 

 Moina rectirostris. Arbeiten Zoolog. Inst. Univ. Wien, 11., Taf XI. -XIV., 1879. 

 The summer eggs are parthenogenetically developed within the brood-cavity of the parent. 



