54i8 Mr. W. S. Macleay's Anatomical Observations 



Tentacula about twenty-six, simple, subulate, alternately long 

 and short. 



Anterior nervous tubercle with many spirals. 



Branchial cavity occupying the whole length of the animal. 



Pharynx situated at the bottom of the cavity of the body. (Eso- 



t phagus descending, and turning short round near the cardia 

 into a cylindrical horizontal stomach, which is striated ex- 

 ternally, and occupies with the pylorus (which turns round 

 and lies parallel to it) the whole of the bottom of the cavity. 

 Intestine very long. Rectum ascending, almost vertical, 

 terminated by an anus margined. 



Ovary one, situated on the left side, between the branchial pouch 

 and the tunic. It consists of a trifurcated, cylindrical stem, 

 having at the base, on one side, a forked branch, on the 

 other a simple one, all of the same thickness. 



This is a very singular animal in outward appearance, as it 

 presents to the simple view no external orifices, and is shaped 

 very much like an acorn. It appears to have been attached to 

 some small pebbles by its base, some of which remain aggluti- 

 nated to it, and give it a wrinkled appearance below. The upper 

 part of it is coriaceous, rather smooth and subpellucid ; for on 

 compressing the body between the finger, the three branches of 

 the ovary are very distinct. The colour of our specimen in spirits 

 is cinereous. The top of the cylindrical body is rather flat, but 

 rounded off" at the sides. On applying a very strong power, we 

 observe, at least in the only specimen I have had the means of 

 examining, four apertures. Two of these are so large as to be 

 visible with the naked eye, but are not the branchial and anal 

 orifices, which are exceedingly minute. The two false apertures 

 form a triangle with the branchial orifice, the space between them 

 being rugose. The first is a semicircular cleft, which I believe to 

 \ ,:.,,, . be 



