125 



perceptible in the smaller specimens. By carefully turning back the 



outer edge of the girdle in the largest specimen, after removing the 



posterior plates, but without touching the animal with the dissecting 



knife, the anus was perceptible, with a pellet of faeces impacted in the 



opening. It U exactly in the median line behind as in the annexed 



sketch, very small, and "not on a papilla. It is also a little higher up 



than in the other species. The "cancellated space" noticed by Mr. 



Emerton (as per notice in Ann. Mag. Nat. Hist., Mar., 1874) on each 



side behind the branchiae is a fold or groove containing the ovarian 



fenestrse. There were in this specimen 



three fenestrse on each side, but according 



to Dr. Carpenter the number is variable, 



Prof. Verrill having counted from four to 



six in some specimens. These fenestrse in 



this species are more complicated than in 



most chitons which I have examined. I 



have never been able to satisfy myself that 



there is a true oviduct, and it may be that 



the ova are dehiscent in the perivisceral branchiaf/tfoot; 0, girdle. C ' 



cavity and may be expelled through the 



fenestrae, as they are through the analogous " oviducts or segmental 



organs " of brachiopods. 



The fact that the ovarian openings are not simple apertures, was 

 noticed by me in dissecting chitons in 1869, but I am not aware that 

 attention had been previously called to this fact in print. Their posi- 

 tion had been previously known, but it is not uniform in all chitons. 

 In some the fenestrse are close to the anus and single on each side, 

 and it has been stated that the ovary of one side is sometimes abor- 

 tive. This last I have not yet observed in any species which I have 

 dissected. 



FIELD MEETING AT WEST NEWBURY, THURSDAY, 

 JULY 16, 1874. 



THE meeting this day was very pleasant, and in many 

 of its features different from the usual routine adopted on 

 similar occasions. The forenoon rambles were not exten- 

 sive, and the excursion on the river proved an accept- 

 able substitute. 



