No. I.] THE METAMERISM OF NEPHELIS. 45 



is quoted by Francois (15) as assigning nine neuromeres to the 

 anal ganglia. The ist anal neuromere, XXV, innervates the 

 first of the posterior terminal somites (PL V, Fig. 7), consisting 

 of annulus 102, the somewhat double annulus 103, and the ante- 

 rior half of 104. The 2d anal, XXVI, innervates the anus- 

 bearing somite, the posterior half of annulus 104, and the broad 

 annulus 105, which often shows traces of doubling. The 3d 

 anal, XXVII, innervates the last somite preceding the sucker, 

 which consists of annulus 106 and the "acetabulum," the area 

 lying between the last annulus and the sucker. This area lies 

 in the plane of flexion of the body on the sucker and has lost 

 all trace of annulation. The succeeding seven neuromeres 

 innervate the sucker. The 4th anal, XXVIII, innervates 

 the anterior part of the sucker, immediately on either side of 

 the median plane. The last anal, XXXIV, innervates the 

 posterior part of the sucker in the same way, while the inter- 

 mediate neuromeres supply the rest of the sucker radially 

 between these parts. The XXVth or ist anal somite resem- 

 bles in every particular a normal body somite. The connec- 

 tives to the XXVIth are very short and broad, and they 

 become shorter and more nearly uniform in breadth with the 

 body of the ganglion as we continue backward. They preserve 

 their characters as connectives, however, as is shown by the 

 oblong slits in the central fibrous portion, until the XXXIId 

 neuromere is reached, when the slits cease. The nerves of the 

 XXVIth and succeeding neuromeres are single, and the details 

 of their fusion have already been described under the " Leydig's 

 cell." The arrangement of the capsules is interesting, for they 

 help to give evidence of the relations between Clepsine and 

 Nephelis (Fig. i in the text). The ventral capsules of a normal 

 neuromere lie one in front of the other, so that the line separat- 

 ing them is transverse. This obtains in XXV, XXVI, and 

 XXVII, the first three neuromeres of the "anal ganglia." 

 But in XXVIII and the succeeding neuromeres the ventral 

 capsules lie side by side, the line separating them being 

 longitudinal. 



16 Ph. Fran9ois ; Contribution a I'etude du systeme nerveux central des hiru- 

 dinees. Poitiers. 1885. 



