596 MATNARD M. METCALF, 



Plate 36. 

 Reference letters. 



a.s.n anterior siphonal nerve m muscle 



C-f ciliated funnel n nerve 



cl. ep cloacal epithelium ph. h peripharyngeal band 



d duct of neural gland ph. ep pharyngeal epithelium 



d.r dorsal raphe p.s.n posterior siphonal nerve 



ep epidermis r. h. s rapheal blood sinus 



f region where the ganglion and r. d rapheal duct 



neural gland are fused together r.n rapheal nerve 



gg ganglion (brain) x in Tig. 36 nerve from ganglion 



gg' in Pig. 36 rapheal ganglion, a to ciliated funnel: the same as 



ganglionic swelling upon the n in Eig. 37 



rapheal nerve y in Tig. 37 point where section 



gl neural gland is slightly torn 

 I in Pig. 37 lumen of the neural gland 



Pig. 24. A ventral view of the intersiphonal organs of Styela 

 plicata Les. X 10 diameters. 



Pig. 25. A parasagittal section of the intersiphonal organs of 

 Styela plicata Les., a little to the right of the median plane. The 

 section is slightly oblique the anterior end being a little further re- 

 moved than the posterior from the median plane. y(^ 111 diameters. 



Pig. 26. A dorsal view of the intersiphonal organs of Polycarpa 

 glomerata Ald. The dorsal branches of the neural gland, four in 

 number, have been cut away. 



Pig. 27. The posterior end of the ganglion and the rapheal duct 

 of Polycarpa glomerata Ald., viewed from the right side. In this in- 

 dividual the rapheal duct extended further down than in any of the 

 seven other specimens examined. 



Pig. 28. A diagrammatic sagittal section through the intersiphonal 

 organs of Polycarpa glomerata Ald. By combining parts of five sec- 

 tions I have drawn what would be an accurate sagittal section of an 

 individual in which the lateral curvature of the ciliated funnel had 

 been straightened out. X ^^'^ diameters. 



Pig. 29. A ventral view of the intersiphonal organs in Molgula 

 manhattensis Vekeill. X about 35 diameters. 



Pig. 30. A sagittal section through one of the ganglionic swell- 

 ings upon the rapheal nerve of Molgula manhattensis Verrill. X '^^^ 

 diameters. 



Pig. 31. A ventral view of the intersiphonal organs of Molgula 

 arenosa (?). X "^1 diameters. 



Pig. 32. A parasagittal section through the intersiphonal organs 

 of Molgula arenosa (?), considerably to the right of the median plane. 

 X 55 diameters. 



Pig. 33. An oblique longitudinal section through the intersiphonal 

 organs of Eugyra pilularis Vekeill. The plane of this section is in- 

 dicated in Pig. 34 by the line which passes through the ganglion and 



