1911] Michael: Chaetognatlta of the San Diego Region. 73 



seminal vesicles. Interval from anterior fin to posterior fin is rather 

 large, varying from 16 to 17 per cent. 



Seising jaws 8, Anterior teeth 5, Posterior teeth 9. The width of the 

 fins could not be determined, owing to the fact that a considerable por- 

 tion had been torn away. Furthermore, the vestibular ridge could not 

 be seen without dissection, which was impossible under the circum- 

 stances. 



The following measurements were made : 



Length 5-5.5 mm. 



Width 6 per cent 



Tail 29 per cent 



Anterior fin in length 12.7 per cent 



Anterior to posterior fin 16.3 per cent 



Posterior fin in length 25.6 per cent 



Per cent of posterior fin in front of septum 43 



Tail to ventral ganglion 68 per cent 



Conant (1896, p. 85) found that -S*. tenuis resembled S. 

 hispida very closely. He says: "Shape of fins, of seizing hooks, 

 corona ciliata, accessory longitudinal septa in caudal segment, 

 number of tactile prominences, and musculature of body, — as in 

 S. hispida." That they are not the same species Conant (1896) 

 recognized because S. tenuis attains sexual maturity at such a 

 small size. In addition, it differs from S. hispida in that the 

 anterior fins originate at the ventral ganglion, and that there 

 is less than 50 per cent of posterior fin in front of tail-septum. 



Ritter-Zahony (1910) places S. tenuis in the synonymy of 

 S. hipunctata. The fact that there is more than 50 per cent of 

 posterior fin in front of tail-septum, and that there is a consider- 

 able interval between anterior fin and ventral ganglion in 8. 

 hipunctata makes me skeptical of such synonymy. Add to this 

 the fact of sexual maturity in 8. tennis at a length of 5 mm., and 

 it becomes readily distinguishable from all other species, with 

 the possible exception of S. minima. 



BRIEF DESCRIPTIONS OF SPECIES NOT YET TAKEN FROM THE 

 SAN DIEGO REGION 



For the benefit of those future investigators who may have 



occasion to identify the Chaetognatha of this region, I have 



included brief descriptions of the species not yet taken from 



this vicinity. Such species are Sagitta decipiens, 8. sihogae, 8. 



ferox, 8. regularis, 8. pidchva, 8. hedoti, 8. macrocephala, 8. 



