MOSS’S POLYSTIGMATIC APPENDICULARIAN. 61 
are just those points which furnish an important clue to 
the real structure and affinities of the animal. 
In Fol’s beautiful and invaluable ‘‘ Etudes sur les 
Appendiculaires du Détroit de Messine (1872)”’ we find 
a detailed description, together with good figures, of an 
aberrant Appendicularian, Kowalevskia tenwis, in which 
these four peculiarities again present themselves. Kowa- 
levskia tenuis possesses, equally with Mossia, a truncated 
buccal extremity, ‘‘sans appendices ni protubérances,”’ 
and a tail of considerable length, ‘‘lanceolée et pointu 
en arriére,’ of which, moreover, ‘‘la partie antérieure est 
étroite et va en s’élargissant tres-lentement du point d’ 
insertion jusqu’ au maximum de largeur,’’ which, as in 
Mossia, is to be found ‘“‘a son tiers postérieur.”’ The 
anus is not easy to see in Kowalevskia tenuis, but Fol 
made out that, upon slight pressure, the feces always 
escaped at one point ‘‘au coté droit du corps, a la partie 
droite et ventrale du rectum. En sorte que l’existence, 
en cet endroit, d’un anus trés-contractile est plus que 
probable.’’ After careful search, Fol arrived also at the 
conclusion that heart and endostyle are entirely absent in 
his species (see Plate V. figs. 2 and 3). 
Thus there is seen to be a strong prima facie case for 
the generic identity of these two peculiar forms of Appen- 
dicularians. There remains, however, the consideration 
of two apparent discrepancies in regard to the structure 
of the pharynx and the presence of atrial apertures. 'T'o 
take the second first,—there 1s no attempt in Moss’s figure 
to represent the external apertures of the two branchial 
(atrial) canals which exist in all other forms. Either they 
do not exist as such, and the supposed stigmata lead 
directly to the exterior; or they have been overlooked. 
The former alternative cannot easily be reconciled with 
Moss’s description. For he expressly states that the 
