238 
ALFRED GIARD. 
characteristic features of the group of the Vermes thus 
limited is the existence, in all the animals of this group, of 
a gemmiparous reproduction (sporocysts, echinococci, &c.). 
This peculiarity only disappears in the higher worms, the 
Turbellarians, which are related to the rest of the group by 
so numerous and so important morphological features that 
no serious zoologist will entertain the idea of separating 
them from the Trematoda and Cestoda, in order to approxi- 
mate them to the Annelids, as has sometimes been done. 
Amongst the animals formeily classified with the preceding, 
some (Bryozoa, Annelida, and satellite-groups) are intimately 
related to the true Molluscs, with which I unite them to con- 
stitute the group of the Gymnotoca, whilst others form an 
assemblage which we may call the Nematelmia, including 
therein the Nematoidea, the EcMnorhynchaj the Desmoscole- 
ciday the G aster otricha, &c. The Tunicata must be placed 
at the base of the phylum of Vertebrata. Budding from the 
interior of sporocysts is found, it is true, in other classes of 
the animal kingdom. Leaving aside the somewhat aberrant 
cases found among Arthropoda, we see in certain Rotifers 
{Callidina) an internal gemmiparity very similar to that of 
the Vermes. Further, the Gasterotricha, the parent-stock 
of the Rotifers and perhaps of all the Gymnotoka, appear 
to me to he readily connected with'the Vermes by means of 
the Orthonectida. 
We must not forget that the external resemblances between 
the Orthonectida, Gasterotricha, parasitic Rotifera, &c., 
are further increased by the similar manner of life obtaining 
in all these animals. OpMcoma, like Linens gesserensis and 
Leptoplana tremellaris^ inhabits muddy bottoms. The same 
is true of the limicolous Annelids and of Nebalia, on which 
we find as parasites certain degraded Rotifers (Balatro and 
Saccobdella). But the Orthonectida are in any case very 
inferior to the most degraded Rotifers, and represent, without 
any doubt, after the Gastraeada, the first step of the sub- 
kingdom Metazoa. 
I must add here that, according to a letter from Leuckart, 
the embryo of Distoma resembles the Orthonectida in a most 
astonishing manner, a fact which tends to confirm the 
position which I have assigned to this group among the 
Vermes. 
Beneden, ‘ Bulletins de I’Acad. de Belgique/ 2e serie, t. xli and xlii, 
No. 7, 1876 ; also Abstract, with Plate, in • Quart. Journ. Mic. Science/ 
vol. xvii, 1877, p. 132. 
