LUMBRICUS TERRESTRIS L. MULLER 



The mouth is situated on the first 

 segment and is surmounted by a pro- 

 stomium. The anus is terminal on 

 the last segment. About one-quarter 

 or one-third the entire length from 

 the anterior end is found a shiny belt 

 occupying six or seven segments; this 

 is the clitellum. Careful counting of 

 the segments will reveal that the 

 clitellum begins with the thirty-first 

 or thirty-second and ends with the 

 thirty-seventh segment, in other 

 words, it has always a definite posi- 

 tion. By passing a finger from the 

 rear end of the worm forward along 

 the ventral surface and on each side, 

 one will feel the stiff bristles situated 

 in each segment and forming two 

 ventral and two lateral lines. Each 

 line consists of two rows and each 

 segment has therefore eight bristles 

 or chetce commonly marked as a, b, 

 c, and d, beginning with the ventral 

 bristles. The first and last segment 

 have no bristles. The ventral bristles 

 of the twenty-sixth segment situated 

 on glandular papilla are often, but 

 not always modified as long genital 

 cheta. There are two openings of 

 seminal receptacles between the 

 ninth and tenth segments and two 

 similar openings between the tenth 

 and eleventh segments in the lateral 

 lines; two female genital pores on 

 the fourteenth segment just above 



IV 



FIG. 20. Sparganophilus 

 lamesis, general anatomy after 

 Bentam, from Cambridge Nat- 

 ural History. I-XVIII, seg- 

 ments; i, 4, 6, perivisceral ves- 

 sels (6 is one of the hearts); 2, 

 3, 7, dorsal vessel; 5, sper- 

 matheca; 8, sperm sacs; 9, 

 intestino-tegumentary vessels; 

 10, ovary; n, 12, integument- 

 ary vessels. 



