Eastropic Chaetognatha — SUND 
283 
4-9; posterior teeth 8-17. Single pair of lateral fins restricted to tail segment; wide, with 
rounded lateral borders; reaching seminal vesicles. Caudal fin close to, but not touching, 
seminal vesicles. No intestinal diverticula. Collarette voluminous, all or part frequently 
missing, extending from head to anterior border of fins, confluent with fins. 
BODY LENGTH LENGTH OF TAIL ANTERIOR POSTERIOR 
IN MM. SEGMENT (iN Vo OF HOOKS TEETH TEETH 
TOTAL BODY LENGTH) 
Eastropic specimens: 
7.1 
35.2 
8 
6-7 
12 
5.8 
36.2 
8 
6 
15 
5.6 
37.8 
9 
6 
15 
5.1 
37.2 
9 
6 
17 
4.9 
32.6 
8 
5 
13 
4.4 
38.6 
9 
6 
8 
4.0 
35.0 
9 
4 
Hidas specimens: 
1.6 
34.2 
9 
9 
15 
6.9 
34.7 
9 
9 
17 
6.8 
35.2 
9 
7-8 
11-14 
6.3 
36.6 
9 
7 
6.2 
37.0 
9 
7 
17 
KEY TO THE PLANKTONIC GENERA AND SPECIES OF ChAETOGNATHA PRESENT 
IN THE EASTERN TROPICAL PACIFIC 
Key to the Genera of Chaetognatha 
1. A single pair of lateral fins 2 
1. Two pairs of lateral fins, which are sometimes connected Sagitta 
2. Two rows of teeth; one pair of lateral fins restricted to the tail segment, appearing as a 
continuation of a voluminous collarette (one species only: P. draco) Pterosagitta 
2. One row of teeth; one pair of lateral fins extending over the trunk and tail segments ... 3 
3. Single pair of lateral fins extending from seminal vesicles over the posterior 14 of the 
trunk segment. Teeth long, tapered, tips converging . Krohnitta 
3. Lateral fins slender, not reaching seminal vesicles, extending anteriorly to ventral gan- 
glion. Teeth short, not converging (one species only: E. hamata) Eukrohnia 
Key to the Genus Krohnitta 
1. Body slender, transparent; fins very wide, rounded, widest at level of tail-septum; short 
ovary with rounded ova; collarette absent subtilis 
2. Body robust, opaque; fins not rounded, widest behind tail-septum; ovaries contain large 
cuboidal ova; collarette sometimes evident as a narrow band of epidermal thickening 
extending from neck to anterior edge of fins pacifica 
Key to the Genus Sagitta 
1. Anterior fins start some distance posterior to ventral ganglion 
2 
