.JOURNAL OF MICROSCOPICAL SCIENCE. 



DESCRIPTION OF PLATE II. 

 Illustrating Mr. Busk's paper on Sagitta bipunctata. 



Kig. 

 1. — HaijUta hipiivdata magnified, dorsal vie\v 

 a, a. Anterior pair of lateral fins. 

 h, h. Posterior jiair. 



c. Caudal fin. 



d. Spermatic cavities. 



e. Ejaculatory sac. 

 2. — Dorsal aspect of the head. 



2*. — Inferior aspect of head and part of tranl<, to show an appai'ent pro- 

 cess, observed on one or two occasions, probably a parasite. 

 3. — Ventral as|)ect of the head. 



a. Oral denticles. 



h. Mouth. 



c. Hooks. 

 4. — Magnified view of jwsterior portion of trunk and part of the caudal 

 portion of the body. 



a, a. Ovaries. 



h. Placental tract. 



c. Orifice of oviduct, wliicli opens however above the fin and 



not below it, as here represented. 



d. Anal opening. 



e. e. Ejaculatory sacs. 



/, /. Spermatic sacs in the caudal portion of the body. 

 5. — A more highly-magnified view of one of the ejaculatory sacs, with 

 spermatozoa swarming about the orifice (viewed on the side). 



a. The sac. 

 6. — A more highly-magnified view of one of the ovaries. 



a. Placental tract, enclosing — 



h. A ca^cal canal ; 



c. Ova, still attached to the placental tract ; 



d. Orifice of oviduct. 



7. — Cephalic ganglion and its branches (Huxley). 



a. The ganglion, compiosed of nerve cells in the central portion. 

 h, b. Anterior pair of nerves, going to supply the buccal 

 muscles. 



c, c. Posterior pair, or optic nerves. 



d, d. Middle pair, which ]iass downward on cither side of the 



oesophagus, to join the ventral ganglion. 

 /, i. Optic ganglia, which, according to Huxley, are contained 



in capsules. 

 k, k. The eyes. 



I, I. A ganglioform enlargement of the optic nerve. 

 8. — The ventral ganglion. 



d, d. Anterior pair of nerves, going to the cephalic ganglion. 



e. A loose capsular investment of the ganglion. 

 /, /. Posterior pair of nerves. 



</, g. Lateral nervules. 

 h, h. Central tract of white nervous matter. 

 9. — Spermatic vesicles and cells. 

 10. — Diagrammatic view of the nervous system, taken from Krohn, with 



the omission of the supposed ]iosterior cephalic loop. 

 11. — Mature spermatozoa. 

 12. — Spermatozoa in various stages of development. 



a. Early stage. h. Later stage. 



