REPORT ON THE PTEROPODA. 
93 
ventrally below tbe moutli ; on the contrary they completely surround the mouth, 
dorsally and ventrally, without being in any way continued on to the fin. Their 
disposition recalls, especially in the young specimens, that of Peraclis . 
The two tentacles are absolutely symmetrical, and the right one is not enclosed in a 
sheath. The penis is situated on the dorsal surface of the head, in the median line in the 
adult. 
The orientation of these animals is given but unsatisfactorily in malacological 
descriptive works. This is especially true, as we shall see, of Cymbulia, and is due to 
the marked external difference between the Cymbuliidse and the other Thecosomata. 
From a systematic point of view the family is yet more unsatisfactorily known than 
even the Limacinidse. For the shell of the adult Cymbuliidse not only has a morpholo- 
gical import different from that of the other Thecosomata, but is also different structurally, 
and does not admit of being preserved in the dry state. In consequence of which it has 
received but little attention from the “dry-skin philosophers”; and as in the general 
systematic treatment of Mollusca, at least as regards genera and species, the conchologists 
have the upper hand, the result is that our knowledge of the systematic relations of this 
group is in a rudimentary state, and that the information we possess of the animals is of 
a most restricted and incomplete character. 
It is very unfortunate that the materials as yet at command have not enabled me 
to make any great progress. I can only interpret more clearly the known facts, correct 
certain errors, and complete or elucidate certain observations. 
The generic names hitherto applied to the forms in this family are four in number : — 
Corolla, Cymbulia, Gleba, and Ticdemannia. Of these four names, two, namely Corolla 
and Ticdemannia, are, as we shall afterwards see, synonymous with Gleba. There 
only remain Cymbulia and Gleba to take account of. 
But to distribute the different species of C3^mbuliidae between these two genera, and 
to determine their respective boundaries, is no easy task, especially with the slight 
utilisable material at command. This difficulty is increased by the fact that we have 
shells without animals and animals without shells, and that the latter have been 
described as naked, while in reality all the adult members of this family possess the 
so-called “ cartilaginous ” pseudoconch. 
If we survey the different specific titles given to forms referred to the Cymbuliidse, 
we find, in addition to the four names of genera, the following seventeen names of 
species : — 
Cymbulia calceola, Yerrill. 
Cymbulia cirroptera, Gegenbaur. 
Cymbulia norfolkensis, Quoy and 
Gaimard. 
Cymbulia ovata, Quoy and Gaimard. 
Cymbulia per oni, cle Blainville. 
Cymbulia proboscidea, Gray. 
Cymbulia 'punctata, Quoy and Gaimard. 
