AN UNDESGRIBED A CRANIATE. 21T 



posterior to or at the anus, a blunt process grew out from the 

 healed-over wound. On examination by sectioning, this process was 

 found to contain notochord, anus and nerve tube and to be covered 

 by a complete new epidermis. Here, as in the tadpole or sala- 

 mander, there seems to be a regeneration of each tissue to form 

 new tissue of its own kind. The epidermis was continuous with 

 the old one and underlaid by a delicate connective tissue lamella 

 continuous with the much thicker one under the old epidermis. 

 The nerve tube was a collection of a few large cells continuous 

 with the walls of the old nerve cord and surrounding a relatively 

 large central lumen. The notochord had grown out very much as 

 in the figures of Siredon given by Barfurth and was enclosed in a 

 delicate sheath continuous with the stout sheath of the old cord. 

 The digestive tract was continued to the surface of the body where 

 its lining cells became continuous with the outer epidermis. The 

 muscles of the last pair of myotomes appeared to be broken down 

 into an amorphous mass that was continuous with a new meso- 

 dermal formation in the new tail. This mesoderm mass consisted 

 of a loose sponge-work of cells arranged in the proximal part 

 of the new growth so as to surround segmentally-placed cavities. 

 Large blood, or coelomic, spaces full of coagulum or lymph also 

 occurred in this part of the new outgrowth. 



With sufficient care the specimens might well have regenerated 

 complete post anal regions as far as could be surmised from these 

 few observations. 



Coming now to the chief anatomical peculiarities of this new 

 Acraniate we find them expressed in the asymmetry of the repro- 

 ductive organs and in the character of the fins. 



In the living animal the reproductive organs, ovaries and testes, 

 may be easily seen through the body-wall, but much more readily 

 from the right side (Fig. 1) than from the left (Fig. 2). This is due 

 to the fact that the gonads form a single series present only upon the 

 right side of the animal and are not paired as in all other Acraniata 

 and in most all Craniata. From the right this single series of 

 gonads shows plainly through the wall of the atrium while from 

 the left it is more or less concealed by both sides of the pharynx, 

 the left wall of the atrium and, in part, by the caecal pouch that 

 lies on the left of the animal. 



