THE ANATOMY OF SCALTBREGMA INFLATUM. 307 



anterior to this, and tlie cirri and secondary annulation of the older segments. 

 Tlie dorsal cirri are formed earlier than, and are larger than, the ventral cirri. 

 The slightly raised area in the median line marks the position of the nerve- 

 cord (which is uon-gangliouated ; the appearance of ganglionation presented 

 by the specimen is due to tlie contraction of the body-wall). The anal cirri 

 on one side have been cut off close to their bases, x 80. 



Fig. 7. — Posterior aspect of a parapodium from the specimen drawn on the 

 preceding Ggure. The parapodium was situated three segments in; front of 

 the oldest segment shown in Fig. 6. x 80. 



Fig. 8. — The thirty-fifth parapodium of the specimen drawn in Fig. 1. 

 The dark area {Cirr. Gl.) in each cirrus marks the position of the gland, which 

 is seen by transparency through the epidermis of the cirrus. The sense organ 

 is situatedjn and hidden by the small papilla seen between the bases of the 

 notopodium and neuropodium. x 20. 



Fig. 9. — The thirtieth parapodium of a specimen 14 mm. long, which was 

 stained, cleared, and compressed in order to bring the muscles into the same 

 plane as the other structures. The typical parts of a parapodium are shown 

 — the dorsal and ventral cirri with their large gland-cells, the notopodium 

 and neuropodium each with simple and furcate setae, the sense organ and its 

 retractor muscle, and the protractor muscles of the setal sacs, x 80. 



Fig. 10.— Five gland-cells from one of the glands shown in the preceding 

 figure. The pointed ends of these unicellular glands pierce the epidermis and 

 open on the free surface. Each gland contains a large number of rod-like 

 bodies. The nucleus of one of the cells is seen near its inner end. x 500. 



Fig. 11. — Rods from the parapodial glands of the specimen shown in Fig, 1. 

 Compare their size with that of the rods from a much younger specimen shown 

 in the preceding figure. X 500. 



Fig. 12. — A thick longitudinal section (25 /x thick) through an aunulus of 

 a specimen 14 mm. long, to show the unicellular glands of the skin, the cir- 

 cular and longitudinal muscles, and the annular nerves. N. Chcet. Annul, is 

 a section of the nerve of the chsetigerous annulus, which is larger than the 

 nerve [N. Annul.) supplying the following annulus. x 270. 



Fig, 13. — Dorsal view of the anterior end of a specimen of Fumenia 

 crassa 29 mm, long, to show the prostomium, nuchal grooves, peristomium, 

 and the first and second chsetigerous segments, the latter bearing two small 

 gUls, X 9, 



PLATE 14. 



All the figures relate to Scalibregma inflatum. 



Fig, 14. — Dissection of the anterior portion of the specimen drawn in 

 Fig. 1, to show the general arrangement of the internal organs. The principal 

 features shown are the four anterior diaphragms, the alimentary canal, and 



