44 



BULLETIN 69, UNITED STATES NATIONAL MUSEUM. 



the median line. It measures 180 to 2S0/j, in length, and 45 to 55/0, in 

 maximum thickness. It is covered with a la3^ei- of longitudinal 

 muscles, thickest near the middle and diminishing in thickness toward 



cir. 



lOOu. 



Fig. 33. — Dioechis acuminata : Sexually mature segment, dr., Cirrus, c. p., Cir- 

 rus POUCH, ov.. Ovary, t.. Testicles, ves. sem.. Seminal vesicle, yg.. Yolk 



GLAND. 



each end of the pouch. Within the cirrus pouch the vas deferens is 

 swollen to form a seminal reservoir occupjdng more or less of the 

 cavity of the pouch, according to the quantity of spermatozoa con- 



c.p 



ves. sem. 



ext . muse , 



d.ex 



▼ . ex. 



sem. recept. 



Int . muse. 



lOQu.. 



Fig. 34. — Diorchis acuminata : Sexually mature segment, transverse section. 

 c. p.. Cirrus pouch, d. ex.. Dorsal excretory vessel, ext. muse. Outer longi- 

 tudinal muscles, int. muse. Inner longitudinal muscles. I. n.. Nerve cord. 

 ov.. Ovary, sem. recept.. Seminal receptacle, v. ex., Ventral excretory vessel. 

 ves. sem.:. Seminal vesicle. 



tained. The cirrus (figs. 33, 35, cir.) is unarmed; w^hen extruded it 

 measures 6 to 8/a in diameter, wdth a globular swelling at its base 14 

 to 16;u in diameter. Wlien fully extruded it measures over 150/x in 

 length. 



