new Recent Pharetronid Sponges. 518 



and that tlie scleroblasts may be extremely modified eu-> 

 velopin.2,- telmatoblasts. I have no direct evidence to bring 

 forward in support of this iiypothesis, and tliere is much to 

 say against it, but the investigation of the remarkable cement 

 formation in LithoninsB and Merlinse affords, I think, some 

 justification for the statement that a theory of this kind may 

 be worth considering. 



List o/Lithonin£e and Merlin89. 



Subfain. Lithonin^e, Doderlein. 



1. Petrostroma schuhei Doderlein. Japan, 109-218 fms. (i. p. 15.) 



2. Fleet roninia hindeili.\vk}^. Funafuti, 50 fnxs. (4. p. 345. ) 



A minute specimen provisionally placed in genus Plectroiiiuia, Hiude 

 (3. p. 51. ), but doubtfully belonging there. 



3. Minchinella larnellosa Kirkp. New Hebrides, 70 fms. 



Subfam. Merlins. 



4. Merita normani Kirkp. Porto Santo, 60 fms. 



Index of Literature. 



(i) Doderlein, L. " XJeber die Lillionina," Zool. Jahrb. Bd. x. Syste- 

 matik, 1879. 



(2) IliNDB, G. J. Catalogue of the Fossil Sponges in the British 



Museum. 1883. 



(3) . " Some remarkable Calcisponges from the Eocene Strata 



of Victoria (Australia)," Quart. Journ. Geol. Soc. vol. Ivi., Feb. 1900, 



{l a) Ijima, I. " Studies on the Hexactinellida. Contrib. I. (Euplec- 

 tellidtB)," Journ. Coll. Sci. T5ky5, vol. xvii. Art. 9. 1902.' 



(4) Kirkpateick:, R. " Description of Sponges from Funafuti," Ana, 



& Mag. Nat. Hist. (7) vi. 1900. 



(5) Lister, J. J. Astrosdera willeyana, the Type of a new Family 



of Sponges. A. Willey's Zoological Results, part iv. Cambddge 

 University Press, 1900. 



(6) ZiTTEL, K. A. VON. " Studien iiber fossile Spongien," Dritte 



Abth. Abhand. k. b. Akad. Munchen, Math.-Phvs. CI. Bd. xiii. 

 1879. 



(7) . Grundziige der Paliiontologie, Abth. i. Invertebrata. Ed. 2, 



1903. 



EXPLANATION OF THE PLATES. 



Plate XIII. 



3Iinchinella lainellosa, gen. et sp. n. 



Fiff. 1. Minchinella larnellosa. Specimen A. The type. Poral surface. 



Nat. size. 

 Fiff. 2. The same ; oscular snrface. Nat. size. 

 Fiy. 3. Smaller specimen, B ; poral surface. Nat. size. 

 Fir/. 4. Pore-chimneys of spec, A, X 3. 

 Fig. 5. Oscular chimneys of spec. A, X 3. 

 Fiff- 6. Poral chimneys of spec. B, X 3. 



Fiff. 7. Excurreut canals with flagellated chambers (.spec. B), X 90, 

 Fi(/. 8. Collar cells, x 880. 

 Fi;/. 9. Telmatoblasts (mortar cells), x 880. 

 Fi(/. 10. Embryo, section, X 125. 



