INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 057 



is large, with well-marked suckers, but no Looks or neck. The lower 

 edge of the segments is very distinct, rounded, and bears a row of 

 filaments resembling those of the suckers of Ligula. The genital 

 apparatus is single, and occurs on the same side in all segments, the 

 female opening on the inferior edge, the very prominent penis in the 

 middle of each. The penial sheath early occupies most of the seg- 

 ment, but is iiltimately absorbed, owing to the development of the 

 ova. The ova resemble those of the Tcenice inarmatK. 



In considering the development of the Cestodes, M. Moniez points 

 out that the imperfect segmentation of the ovum, as shown by Teenia 

 serrata and expansa, is by no means the rule in this group. And in 

 these cases the extruded cells do not aid in the formation of the cells 

 of the blastoderm, but they are the homologues of the polar corpus- 

 cules, and only occur when these are wanting, and vice versa. The 

 true relations of the extruded cell are seen clearly in a new species of 

 Cestode, found at Wimereux, in Squatina angelus. Here the original 

 egg-cell, after dividing into two, becomes distended with liquid, and 

 ascends to the surface of the yolk, and is ixsually destroyed shortly. 

 On the other hand, the primary cell is detached in the form of an 

 ordinary polar vesicle in species such as T. anatina, &c., in which the 

 segmentation appears to be regular ; or else it persists, and increases 

 greatly in size (in T. serjientulus and others), in which case, the blasto- 

 dermic cells surround it, and may even conceal it, after giving the 

 embryo the appearance of being hollow. In a Botlirioceplialas inhabit- 

 ing the salmon, these processes are exactly like those of Liyula, except 

 that tlie embryo is developed within the parent, and that the amnion, 

 corresponding to the embryophore, is granular, and shows no analogy 

 with the corresponding membrane in Ligula. The embryo is seen in 

 Teenia serpentulus, and less distinctly in T. cuciimerina, gradually 

 to become hollow. Two muscles, strongly refractive in appearance, 

 arc especially noticeable, passing backwards from the cephalic bulb, 

 to become attached at the posterior end of the cavity thus formed. 



The segmental organs of the Cestoidea are not the organs described 

 by Fraipont as such, but, as is the most clearly seen in Leuckartia, 

 consist of the so-called vagina, which opens at one end into the uterus, 

 and at tlie other into a wider chamber connected with the ova. This 

 chamber lias proper muscles, is attached on all sides to the surround- 

 ing tissues, and the cells which line it contain a coloured material ; 

 the tube leading to it is ciliated throughout. It thus fulfils all the 

 requirements of a typical segmental organ ; and it is known to exist 

 in tliis form in the higher Tani(i\ 



Solenophorus megacephalus.* — -M. Moniez in this note criticizes 

 the account given by M. ruirier.f The later observer has only 

 been able to detect two (one on either side) in place of six longi- 

 tudinal vessels. Without dealing with any points in discussion 

 between these two naturalists, it is of importance to direct attention 

 to the explanation which ]\r. ]\[oniez gives as to the very ditfurent 

 accounts of various observers. As in all the lower animals, thero 



♦ ' Hull. Sci. Dcp. (In Nnrd,' iii. (ISSO) p. 113. 

 t Sec this .Iduniiil, ii. (187'.t) p. 2M. 

 VOL. 111. 3 S 



