24 JOURNAL OF MARINE ZOOLOGY AND MICROSCOPY. 



ancestral foot. The figures also illustrate the true application of the 

 terms dorsal, ventral, anterior and posterior to the body aspects in 

 Pteropods and Cephalopods. 



It may now be useful to show in tabular form, the place assigned 

 to the Pterojjods, in the phylum Mollusca, and to give a summary of 

 orders and other divisions : — 



Branch B :— Lipocephala 



(without radula & without " head.") 

 Class I. — Lamellibranchiata (types — 

 Mussel, Oyster, Cockle). 



Phylum :— Mollusca. 



Branch A :— Glossophora 



(possessing a radula). 



Class I. — Gastropoda (types — Whelk 

 and Limpet). 



" II. — Scaphopoda (type — Denta- 

 lium). 



" III. — Pteeopoda (types — Creseis 

 and Clio). 



" IV. — Cephalopoda (type — Octo- 

 pus). 



Pteropoda. 



Order I. — TheCOSOmata ; body protected by a shell. 



Family I : — Hyaljeid-e, shell calcareous or horny, symmetric. Types — 



Hyalaea (horny) ; Creseis (calcareous) ; Cleodora. 

 Family II : — Cymbulinidje, shell slipper or boat-shaped and with some 



short " arms. Types — Cymbulia and Tiedemannia. 

 Family III : — Limacinipje. Type — Spinalis, with spirally coiled shell 



having sinistral flexure, i.e. coiling in the reverse direction 



to that usually seen in Gastropod Shells. 



Order II.— GymilOSOmata ; body naked. 



Family I : — Clionidje, without gills, but with short arms devoid of suckers. 



Type — Clione (Clio) borealis. 

 Family II : — Pneumodermonid-E, with gills at apex of body, and with arms 



beset with suckers. Type— Pneumodermon. 



Cleodora pyramidata is phosphorescent and probably others 

 are also. In Cymbulia, the small chitonous shell is internal. Spi- 

 rialis is the most closely related to the Gastropod form, its pecu- 

 liarities extending to the possession of both- a spiral shell and an 

 operculum. The larvae or veligers of Cymbulia and Tiedemannia 

 also possess opercula. 



Tiedemannia, like the Cephalopods, possessed well developed 

 pigment-spots (Chromatophores) on the surface of the body, doubtless 

 a protective device. 



Delay in Issue. — The Editor extremely regrets the delay that has occurred in 

 the issue of the present number. The causes have been several, the chief being 

 that since the last issue, Mr. Sinel's assistance has been lost to the Station, through 

 his acceptance of the management of an Oyster Culture Company now established 

 in this island. This has naturally thrown much extra work upon the writer, but he 

 believes that the new arrangements he has made, will obviate any similar delays in 

 the future. 



