lA^TRODUCTION. 
The Ciliopoda are comparatively the least immeroiis of all the Mollusca 
which have hcoii treated of, and their occnrrcncc is also limited to a single group, 
the Arrialoor; therefore, the hearing of the class upon the determination of the 
relations of the cretaceous beds is not a very important one. I shall, however, 
say a few woi’ds on this subject at the end of the detailed descriptions of the 
various species. 
As regards the treatment of the class, I confine my remarks to a notice 
of those genera which are represented in the South Indian cretaceous deposits, 
and to a few others closely allied to them. I do not need to repeat the complaints 
regarding the great and well known deficiencies in the preseiit systematic aivange- 
ment of the class, and although I have for many years past devoted considerable 
attention to the study of recent and fossil Ciliopoda, and should have much wished 
to give a somewhat similar review of, at least, the marine genera of this class as that 
given of the Pelecypoda, the present opportunity is not suitable for the pm-pose. 
The task is indeed a very great one, and would involve a large amount of time and 
lahoiu', while the illustrations, which coidd he supplied from the Indian cretaceous 
species, would in no way he sufficient. 
The name with which I have denoted the class on the title may call for an expla- 
nation, though this can scarcely he more than a repetition of what I have repeatedly 
stated on other occasions. Already in my introduction to the South Indian 
Cretaceous Gastropoda, I suggested the substitution of the name Ciliopoda for 
Polyzoa or Bryozoa, and that of Saccopoda for the Tunicata. 
In the introduction to the Pelecypoda, I again stated that, if uniformity in 
the denominations of the different classes of the Mollusca is to be attained, — and 
few will deny its desirability — the locomotive organs appear to be more sixited for 
that pui’pose than the organs of respiration, or the system of cephalisation, which 
in some cases yields merely negative characters. It seemed to me, therefore, most 
pi’acticable to conform the names of the two lowest classes of the Mollusca to those 
of the rest, which are almost generally adopted. There is nothing objectionable 
in the combinations of the names, if we merely associate ndth the word vovq-voIoq 
a signification referring to an organ which facilitates locomotion. In the Tunicata, 
strictly speaking, the whole mantle-sac acts as an organ of locomotion, and, 
therefore, the name Saccopoda seems to me quite as much admissible as that of 
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