•on the under surface corresponding with the lines of cells. 

 These lines are porous. In Discojluslrellaria there are no 

 pores. In Cupularia there are neither pores nor lines. They are 

 secondary fossils described by D'Orbigny in his Paleontologie 

 Francaise, vol. 5, p. 506, 513, pi. G01 and 722 ; Defrance, Diet. 

 Sciences Nat. ; Michelin, Icon. Zooph., pi. 77, figs. 9 and 10. 

 It is necessary to bear these distinctions in mind, as it will be 

 seen they apply to some of our Australian fossil species. It 

 seems that while Busk has employed the genus of Lamouroux in 

 one way, D'Orbigny has done so in another, the latter having 

 priority. 



There is also some difference of definition for the genus 

 Lunulites, for while Busk states that it is never attached at 

 any stage of its growth the Lunulites of D'Orbigny, D'Archiac, 

 Leymerie, and Michelin are attached during their young stage ; 

 and Hagenow (Die Bryoz., d. Maestricht. Kreidebild., p. 100, 

 pi. 12, fig. 15, 16) states that he has seen Lunulites semilunaris 

 and L. Goldfussi attached by the entire surface upon Belemnites. 

 Busk thinks the attachment must have been accidental, but my 

 own opinion is that too much importance is given to the 

 character, as free polyzoa are sometimes found encrusting 

 corals, &c. 



Mr. Busk points out that in all the members of this family 

 there are, in addition to the ordinary cells, others which differ 

 in size, and whose office was variously interpreted until the dis- 

 covery by Mr. McG-illivray of living examples enabled Busk to 

 determine that they were vibracular cells. The purpose 

 served by the vibraculwm is not well understood. The organ 

 consists of a cup containing a muscular apparatus, and of a 

 moveable seta articulated to the cup. The seta is in most cases 

 simple and fine-pointed; but in some of the Selenariadse it is 

 bifid or trifid at the extremity. In Selenaria maculata it is 

 spirally contorted and minutely annulated, so very closely as 

 to resemble the proboscis of a butterfly. It may serve the pur- 

 poses of defence and even locomotion, but observations on the 

 subject are needed. 



Whatever purpose they may serve, they have been made in. 

 the hands of the naturalist useful organs for classification, as 

 will appear from the following division proposed by Mr. Busk 

 in the British Museum Catalogue : — 



FAMILY SELENAMAU.E.* 



Zoarium free orbicular or irregular conical or depressed, 

 convex above flat or concave below, upper surface only celluli- 

 ferous. Zoooecia of two kinds disposed in series or quincun- 

 cially. 



*The orthography in the Crag Polyzoa is Selenariidce. 



