230 BULLETIN OF THE BUREAU OF FISHERIES. 
PLATE XVI. 
Fie. 37. Lamina of gill of young 7. navalis, to show especially the distribution of the gland of Deshayes, 
in which the elements are represented semidiagrammatically. The arrows indicate the course 
of the water over and blood currents through the gill lamina. The epibranchial cavity and 
the blood vessels are indicated by the letters which are placed in these spaces. 208. 
Fie. 38. Transverse section of three laminz of Yylotrya gouldi almost in the line of the lower arrow 
in figure 30. Two interlaminar junctions are shown. The two elements of the gland of 
Deshayes are shown, both as to character and distribution. > 208. 
PLATE XVII. 
Fic. 39. Tangential section of a gill of Xylotrya gouldi to show the distribution of the interlaminar 
junctions. 156. 
Fic. 40. Transverse section of three gill laminze, along the line shown in figure 37, near the tip of the 
lamina, so as to show the interlaminar junctions on one side. > 180. 
Fria. 41. Section of the three most anterior gill filaments at the side of the ‘“‘head.’’ The one to the 
left is the first one and only a half filament. The letters are placed in the epibranchial 
canal. > 430. 
Fic. 42. Group of cells from the branchial groove at the edge of the gill, showing the character of the 
ciliated cells and the mucous cells among them. 950. 
Fre. 43. Section of that part of the branchial groove which connects the two parts of the gill. 430. 
Fie. 44. Section of the duct of the gland of Deshayes between the two parts of the gill (1. e., between 
the main part of the gill and the anterior separated filaments of the head). The epibranchial 
canal is shown to the left and the afferent branchial vein to the right. The great variety in 
the cells in the duct is represented. 695. 
PLATE XVIII. 
Fie. 45. Section of two tubes of the gland of Deshayes from a gill lamina. In the walls of the gill lam- 
ina are shown sections of the dendritic processes which penetrate among all portions of the 
glandular structures. > 925. 
Fries. 46 and 47. Coarser and finer portions of the dendritic processes from the gill lamina of 7. navalis 
represented in figure 37. The distribution and contents of these structures are represented 
in detail. > 1267. 
Fries. 48-51. Four stages in the development of the structures of the second factor of the gland of 
Deshayes. X 1267. 
PLATE XIX. 
Vic. 52. Heart of specimen 2 mm. long, dorsal view. Openings from auricles show through the walls 
of the ventricle. 180. D 
Fic. 53. Heart of young adult. The anterior aorta is represented as turned to one side and the auriculo- 
ventricular valves as showing through the wall of the ventricle. About x 10. 
Fre. 54. Longitudinal section of the ventricle and vessels of a specimen 4 mm. long. The arrows indi- 
cate the course of the blood. The posterior adductor muscle and the wall of the stomach 
represented in part. The anterior end is to the right of the figure. The letters are in 
pericardial cavity and stomach. 272. 
Fic. 55. Longitudinal section of the anterior part of the ventricle and vessels of a specimen 10 cm. 
long. X 272. 
Fie. 56. Group of celis from the main portion of the style sheath. > 575. 
Fic. 57. Same from tubular portion. 575. 
Fie. 58 A. Group of cells from the liver, which show the usual liver structure, and 58 B, from its modi- 
fied portion. 575. : 
PLATE XX. 
Fre. 59. Nervous system of newly attached larva, showing the pleural ganglion still separate from the 
cerebral, and the visceral ganglia still wide apart. The details of the nerves are not shown. 
X 430. 
