474 REPORT OF THE HARVARD AFRICAN EXPEDITION 
is seen. With the development of the segments one of these ducts (correspond- 
ing to the dorsal vessel) loses its identity as a consequence of the development 
of numerous secondary tubules. On the dextral side this tube, which is about 
54u wide, runs across the cirrus organ in the anterior segments, but as it pro- 
ceeds its position is shifted inwards so as to run at the side of the nerve cord 
internal to the cirrus pouch. The fact that transverse excretory vessels run- 

Texr Ficure 1. — Anoplocephala gorillae 
Nybelin, 1927; scolex 
ning along the posterior edge of the segment unite with the main longitudinal 
tube indicates that the latter represents the ventral vessel, but in sections it 
is found to occupy a position, not ventral, but almost exactly in the middle 
of the segment. Cross-section of the segment reveals in addition to the ventral 
vessel and its transverse commissures, a series of thin-walled secondary vessels 
running longitudinally in the dorsal and ventral fields of the medullary paren- 
chyma. The excretory system in this worm is undoubtedly complicated and 
may take the form of a complex network of vessels. 
Reproductive Organs. The strobila is nearly 2 mm. thick, so that only 
the grosser structures of the reproductive system can be distinguished in the 
cleared toto-mounts; for the finer details, a study of thick sections, both longi- 
tudinal and transverse, is necessary. Even with this procedure, difficulties are 
encountered in establishing the complete relationship of the female organs. 
The longest specimen in the collection shows a high degree of arrested develop- 
ment of the reproductive organs. In a few segments near the center of the 
chain in this specimen, the incipient development of an ovary can be seen, 
but no signs of male or accessory male organs are to be found; segments more 
posterior to these do not display any evidence of gonad development. The 
remaining smaller specimens, however, show a more regular development of 
the reproductive organs and it is on these specimens that the study has been 
carried out. 
As the following account of the reproductive system will show, the worms 
have either failed to develop to a fruitful maturity, or the specimens with 
which we are dealing represent immature fragments of worms which have al- 
ready shed their gravid segments. For an interesting account of anomalies in 
the development of the reproductive organs sometimes exhibited by cestodes 
