404 WILLIAM A. HASWELL. 



The mode of protrusion of tlic cirrus is rendered evident on 

 an examination of living animals and of sections of speci- 

 mens witli the organs in various states. The strong muscular 

 wall of the cirrus sac contracts_, and the narrow outer end 

 with which the invaginated tube is continuous becomes thrust 

 out through the genital opening. Further pressure causes 

 the tube to become evaginated as a narrow cylindrical process, 

 the cirrus, with a double wall, the space between the two 

 walls being continuous with the cavity of the cirrus sac. The 

 retraction takes places through the agency of the muscular 

 fibres that have been above referred to as situated in the 

 cavity of the cirrus sac ; when the cirrus is protruded these 

 are put upon the stretch, and each of them is found to be 

 connected internally with one of the myoblasts in the wall of 

 the tube, and to run inwards towards the inner part of the 

 wall of the cirrus sac. 



The ovary (figs. 3 and 6, ov.), as in many other Cestodes, 

 consists of two large lateral portions and a small median 

 isthmus connecting them together, the whole, on a dorsal or 

 ventral view, resembling a letter H, with the limbs thick and 

 near together and the transverse part very short. A trans- 

 verse section shows that each lateral portion is itself double, 

 consisting of a dorsal and a ventral lamina which coalesce 

 internally towards the isthmus. The margins of the laminae 

 are divided irregularly into a number of rounded lobes, but 

 these divisions are (|uite superficial, the substance of the 

 lamina consisting of a mass of ova with no trace of a tubular 

 structure, except that irregular fenestra) occur here and 

 there. The ova are somewhat smaller peripherally, largest in 

 the neighbourhood of the isthmus. The mature ova are 

 ■01 mm. in diameter ; their nuclei, "004 mm. ; and their 

 nucleoli, "002 mm. 'J'hoir cytoplasm appears homogeneous 

 under the highest powers, binding them together in a snuill 

 <|uantity of retiform connective tissue. Enclosing the whole 

 ovary is a membrane having the appearance of a condensation 

 of the parencliyma, but perhaps of muscular character. 



The isthmus, or connecting part, differs widely from the 



