424 REPORT ON ZOOLOGY, MDCCCXLIV. 



ganglion which turn backwards and are united into a 

 ganglion in the abdomen, anteriorly to the middle of the 

 trunk, which ganglion again sends backwards two other 

 branches, which split up at their extremity into a sort of 

 cauda equina. 



GASTEROPODA. 



Alder and Hancock describe two new species of Doris in the Annals, xiv, 

 p. 23U), D.flaaimea, 9 branchiae, allied to tuberculata, but the tubercles and 

 branchial plumes are rather smaller, scarlet red. D mem, white, with 13 

 branchiae. Both species are British. D. elegantula, Philippi, Enum. p. 80, 

 with 11 branchiae. 



Quatrefages (Comptes rendus, xix, p. 193) gives a notice 

 respecting calcareous spicuke in the surface of the body of 

 two minute genera allied to Doris. This is evidently the same 

 fact as that observed by Loven in the young Doris nmricatu, 

 (Vid. Archiv. f. 1841, ii, p. 275.) These calcareous needles 

 belong only to the young state. 



Quatrefages describes (in the Annales d. Sc. Nat. 3me 

 serie, i, p. 129 ; vicl. also Comptes rendus, vol. xviii, p. 13, 

 vol. xix, p. 190, Annals, xiv, p. 28) several new genera, 

 which differ very essentially in their organization from the 

 type of the other Gasteropods, and which, with the pre- 

 viously instituted genera, Eolidia, CaUiojjfea, Cavolina, Glau- 

 cus, Actceon, Placobranchus, which have been placed under 

 the Nudibranchia, as well as with the genus Eolidina, pre- 

 viously described by the same author, would appear to con- 

 stitute a distinct sub-order of Gasteropoda, which he terms 

 Phlebenteruta. Whilst the circulatory organs are described 

 as very simple, and consisting merely of a heart and arteries, 

 the veins disappearing, and whilst in connexion therewith 

 the respiratory organs are wanting, the functions of the 

 branchiae are assumed, in the author's opinion, by the diges- 

 tive canal, which has a very peculiar conformation, and pre- 

 sents a disposition to branching. The anus is also very 

 minute, in some genera appearing to be wanting. As for 

 the rest, there can be no doubt that the animals under con- 

 sideration do belong to the Mollusca ; this is shown by the 



