PEOBOSCTtfA. 65 



iption of Figures. PL I. Fig. 6. Part of a zoarium, 

 X 25 dia., showing the gonocysts. Encrusting Nucleolites orbi- 

 cularis (Phil.). Cornbrash: Thrapston. D. 2063. Vine Coll. 

 PI. II. Fig. 2. A zoarium, X 1 1 dia., from same locality. Shows 

 the var. expansa, formed of fenestrate sheets. D. 921. 



Affinities. This species is distinguished most readily by its 

 much branched zoarium, with its flabellate expansions. Haime 

 founded the species for a single specimen from the Bajocian. 

 Vine's collection includes a large series of fairly good specimens, 

 which enables a fuller diagnosis to be prepared. 



The short, rapidly expanding, fan-shaped branches readily dis- 

 tinguish this from any other Jurassic species. 



Among Cretaceous species it is most nearly allied to Proboscina 

 ramosa (Hag.), as that species was limited in the discussion 

 of the affinities of P. eudesi, Haime. This species was not 

 figured by Hagenow, 1 but D'Orbigny's illustrations appear to be 

 reliable. This species differs from P. jacquoti by having a more 

 convex zoarium and shorter and more crowded zooecia. In the 

 former character P. dilatata, D'Orb., 2 is nearer to the Jurassic 

 species, but that also has the zooecia more crowded and more 

 elevated at their distal ends. 



Among recent species Prob. dilatans (Johnst.) 3 is the closest 

 ally. This, however, is much less flabelliform. 



The formula for this group of species are as follows : 



P. jacquoti, Haime, Jurassic 203 1-12 



P. ramosa (Hag.), Cretaceous 202' 1-8 



P. dilatans (Johnst.), Eecent 203 2-8 



LIST OF SPECIMENS. 



D. 2063. On Nucleolites orbicularis (Phil.). Cornbrash. Thrapston. With 



gonocysts. (Type of Vine's P. ornata.} Figd. PI. I. Fig. 6. 



Vine Coll. 

 D. 903. On Nucleolites orbicularis (Phil.). Cornbrash. Thrapston. With 



gonocysts. (Type of P. thrapstonensis, Vine.) Op. cit. pi. xii. 



fig. 6(P8B). " 



1 Von Hagenow. Mon. Rugen'schen Kreide-Verst. Abth. 1, NeuJahrb. 1839, 

 p. 291. P. ramosa, D'Orbigny, Pal. fran9- Terr. cret. t. v. pi. Dcxxxii. 

 figs. 1-3 ; pi. Dcxxxiii. figs. .1-3. 



2 D'Orbigny. Op. cit. p. 851, pi. Dcxxxii. figs. 4-6. 



3 See Hincks. Brit. Mar. Polyz. pi. Ivii. fig. 3. 



