15 GUSTAV EISEN: PONTOSCO] 



15 



3. Ventral view of the ventral side of the body with the ganglion 



parti)- in optical section, 

 v. gl, ventral ganglion. 

 spth. spermatheca. 



m. muscles connecting the apex of the spermatheca with the body wall. 

 bd. body wall. 

 ep. epidermis of the body wall. 



4. One of the posterior dorsal setae; posterior to the caudal /one, magnified. 

 4 b. The free apex of the former showing the notch or foil:. 



5. One of the ventral set« in the same somite as the one in fig. 4, same ma 



6. One of the setae in the anterior somites, same respective magnification a 



the setae shows any ornamentation. Penial seta- werenot developed in am. 

 all of which were immature. 



Plate II. 

 Pontoscolex corethrurus var. mexicanus. 



7 to 15 are sections through the epidermis, in the equatorial zone of vai . each rci 



one of the unicellular auditory organs together with some of the surrounding support 

 and unicellular glands. In all these figures the letters indicate the same, 

 au. c. auditory cell. 

 o. otosome. 

 • fu. funnel or rcceptaculum of cytoplasm in which the otosome is confined 

 n. nucleus; always surrounded by a cap of reticulated cytoplasm. 

 cc. central cytoplasmic cap, surrounding the nucleus, strongly reticulated. This cap is conni 



with the cytoplasmic floor fl. by a cylinder of cytoplasm. 

 fl. cytoplasmic floor extending across the cell some distance above, but near il 



with the central cap c. c. by means of cytoplasmic cylinder c. cy. generali)- seen in 

 cross-section, 

 c. cy. cytoplasmic cylinder connecting cap c. c. with floor fl. 

 n. e. endings of nerve ganglia or nerve cells, on the wall of the auditor)- cell. Two of thes 

 always found on either side of the center in the immediate vicinity ami in ti: 1 

 torial plane of the floor. 

 r. f. reflexed cytoplasmic filaments, forming the margins of a row of plates an • 

 radii in a circle, and which penetrate into the cytoplasmic funnel ab 

 1. cy. lowest cytoplasmic floor, covering the bottom of the cell and which stands in conn 



with the central floor fl. by means of several ramifications of the latti ally 



lamellatcd. 

 gl. c. glandular cells of the epidermis, 

 s. c. supporting cells of the epidermis. 



pi. plate on which the epidermis is superposed. 

 n. f. nerve fibers probably connecting with the nerve endings on the auditory cell, 

 n. m. nuclei of muscle fibers. 

 I. m. transverse muscular layer. 



7. Auditory cell surrounded by supporting cells. The section is aln licular to the cell, 



having but small portion of the supporting cells to be seen between the cuticle and 



upper roof of the cell. One side of the central cytoplasmic 1 



directly connected with the cytoplasmic floor. On the left hand side again t' 



