224 Scientific Proceedings, Royal Dublin Society. 



rian fenestrse (Mr. Dall illustrates his statement with a diagram). 

 There were in this specimen three fenestras on each side, but, ac- 

 cording to Dr. Carpenter, the number is variable,^ Prof. Yerrill 

 having counted from four to six in some specimens. These fenes- 

 trse are more complicated than in most Chitons which I have exa- 

 mined. I have never been able to satisfy myself that there is a 

 true oviduct (opening externally),'^ and it maybe that the ova are 

 dehiscent in the perivisceral cavity, and may be expelled through 

 the fenestrse, as they are through the analogous ' oviducts or seg- 

 mental organs' of brachiopods." 



Dr. Carpenter (4) says, " in the genus Stimpsoniella, as in 

 Trachydermon (the genus to which Ch. ruber, albus, cinereus, &c., 

 belong), the faeces are expelled through slits close to the caudal lobe, 

 one on each side," It is strange that this able systematic concho- 

 logist should have overlooked the anus, and have mistaken the ori- 

 fices of the oviducts for openings of the alimentary canal and ova for 

 faeces ! 



In another paper Dall (7) states of the following species — 

 Ch. {Trachydermon) albus : " Ovarian openings, single on each side, 

 the posterior end of the gill-row passing behind them. The 

 oviducts, as in some other species, could not clearly be made out." 

 CL tnarmorea (Fabr.) " Oviducts not made out. Ovarian open- 

 ings simple, and close on each side of and a little behind the anus, 

 from which a ridge extends in front of them on each side. But 

 there appear also to be two openings in the vicinity of the fourth 

 or fifth branchia from the posterior end of the gill-rows, one on 

 each side. The contracted condition of the specimens, from the effect 

 of the alcohol in which they were preserved, prevented a satisfactory 

 confirmation of these appearances." Ch. submarmorea (Midd.) — 

 " Soft parts very similar to last in every respect, except that the 



1 I find that in the Ann. Mag. Nat. Sist., 1874, Dr. P. P. Carpenter says 

 (p. 121) : — "Mr. Emerton first observed a great peculiarity in the animal — that there 

 is a cancellated space between the posterior gill and the caudal extremity. Professor 

 Verrill observed that in different specimens there were either one, two, or three rows 

 of holes on each side. The caudal lobe is generally figured as an anal tube ; but in 

 T. rubrum {sic) it is an imperforate muscle, workkig the posterior part of the girdle. 

 The faeces were distinctly seen to escape, sometimes on one side, sometimes on the 

 other, as it appeared to me, from a slit on each side." 



- This was added in M8. in the copy of the Paper Mr. Dall kindly sent me. 



