no CALIFORNIA ACADEMY OF SCIENCES. 



PLATE XXXIX. 



PONTODEILUS MICHAELSENI. 



70. Cross-sectiou of the body iu somite xi, showing the relative thickness of the septa and body-wall, the sepia 

 being very much cupped, showing the cesophagus, etc., of the somite ix, as well as the septum and ciliated 

 rosettes of x. v. v. x. the ventral vessel iu x where it connects with the hearts, v. v. ix. the two forms of 

 the ventral vessel, ijl. septal gland surrounding the connecting vessels in somite ix. There are five pair of 

 these glands, one each iu v, vi, vii, viii, ix. 



71A. One of the nephridia isolated, p. I. posterior lobe of the peritoneal sac of the nephridium. a. I. anterior 

 lobe of the same. u\ windings of the canals where the two folds meet. p./. and a./, posterior and anterior 

 folds of the canal, n. p. nephropore. n. st. nephrostome. spr. spur with four canals, br. bridge. 

 bl. V. blood vessels on the nephridium. 



71B. Nephrostome isolated, m. marginal cells, w. d. wide duet. ncc. neck in which the narrow duct is seen to 

 be branched. 



7"2. An enlarged and somewhat diagrammatic drawing of the course of the ducts, etc.. of the nephridium. The 

 letters indicate the same as in the preceding figure. The canals have been represented as further apart 

 than they are in reality, otherwise their course could not have been clearly delineated. When the nephridium 

 is viewed from above mounted in glycerine, the outlines of the canals are only dimly discernible, being greatly 

 obscured by peritoneal cells and blood vessels, neither of which have been delineated. The shape of the 

 neck varies to some extent, iu some specimens being much wider than in others. 



73. Various forms and sizes of blood-glands from the supra pharyngeal and septal salivary glands. Drawn from 

 paraline sections, hardened iu Formaline, and stained: n. orange G. alcohol, Ehrlich's hsematoxylon amm. 

 b. rose aniline iu hydrochloric alcohol, Bismark brown, and Ehrlich's ha-matoxylon. The latter combination 

 gives by far the finest resTilts, clearly differentiating the blood from the gland-secretion, this being very 

 imperfectly done by the orange G. 



