Reproductive Structures in Chaetognaths — Alvarino 
491 
TABLE 1 
Comparison of Breeding Characteristics of Six Genera of Chaetognatha 
GENERA 
GENERIC NOTATIONS 
BREEDING CHARACTERISTICS 
Eukrohnia 
One pair of fins (from tail to ventral ganglion); 
one pair of sets of teeth 
Brood sac or marsupium 
Bathyspadella ? 
One pair of rayed fins (from tail to near the 
ventral ganglion ) ; no teeth 
Probably as in Eukrohnia 
Krohnitta 
One set of paired fins (from tail to posterior part 
of trunk) ; anterior pair of sets of teeth 
Somewhat similar to 
Eukrohnia 
Heterokrohnia 
One set of paired rayed fins (from tail to level of 
posterior end of ventral ganglion) with a con- 
striction about mid-length; two pairs of sets of 
teeth 
Unknown 
Pterosagitta 
One set of paired fins (from tail to level of poste- 
rior septum) ; trunk covered by thick cuticulae 
(collarette); two pairs of sets of teeth 
Pelagic jelly ootheca 
Sagitta 
Two sets of paired fins; two pairs of sets of teeth 
Free eggs covered by thick in- 
volucrum 
M. W. Johnson for reading the manuscript, and 
for his valuable advice and encouragement. 
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