from the N. W. Coast of Spain. 109 



at all events, any more than that of the Esperia on which 

 they were growing, which merely presents the grey tint of 

 colom-less sarcode. The granuliferous cells represented in the 

 dermal sarcode of fig. 9 might also well stand for the appear- 

 ance and relative size of these Ascidians. 



EXPLANATION OF PLATE VII. 



Mff. 1. Aplysina conieostellata, n. sp., nat. size, growing on the shell of 

 a living mussel (Modiola albicosta ?) ; colour pink- violet or flesh- 

 colour : a, shell ; b h, vents. 



Fig. 2. The same, one of the mammiform eminences, magnified, to show 

 the position of the vents and genera) character of the aculeated 

 surface : a, rays of horny steUates projecting beyond the summits 

 of the aculeations; b, vent, showing its division into smaller vents 

 within. 



Fiff. 3. The same, single ray, still more magnified, to show the manner in 



which the dermal sarcode hanging upon it tent-like forms the 



* aculeation : a a, ray ; b, centre of horny stellate ; c c, subdermal 



reticulated structure covered by the transparent dermal sarcode. 



Ftff. 4. The same, corueo-stellate fibre and ova, magnified 15 diameters : 

 a, foreign object on which the stem-like filament (b b b) is 

 growing ; c c c c c, corneo-stellates ; ddd, thin expansions of 

 horny matter uniting the rays together ; e, cell enclosed under 

 an expansion of horny matter ; /, grain of sand enclosed undei' 

 an expansion of horny matter ; (/ () (j, ova. 



Fifj. 5. The same, portion of ray of stellate, much magnified : a, cortical or 

 horny tube; bb, core or interior presenting parabolical wave-like 

 lines, with their convexities directed towards the free extremity 

 of the ray ; c, cell enclosed xmder a thin expansion of horny 

 matter ; d, the same, enlarged and elongated, with the addition 

 of concentric horny layers round the cell, which now becomes 

 the core ; e, the same, putting forth five buds, corresponding 

 vrith the number of rays in the stellate. Diagrammatic. 



Fiff. 6. The same, extremity of ray, much magnified, to show the com- 

 mencement of a branch whose core is connected with that of 

 the ray : a, cortical or horny tube ; b, core ; c, branch ; d, thin 

 expansion of horny matter covering the branch. 



Fig. 7. The same, piece of horny fibre, still more but proportionately 

 magnified, to show the relative thicknesses of the core and cor- 

 tical tube, also that the latter is formed of layers : a, cortical 

 tube ; b, core. 



Fig. 8. The same, portion of the dermal surface, magnified, showing : — a, 

 the subdermal reticular .structure ; b, the interstices in which the 

 pores are situated. 



Fig, 9. The same, a single interstice, much magnified, and partly covered 

 by the dermal sarcode in which the pores are seen and situated : 

 a a, dermal sarcode, apparently homogeneous, charged more or 

 less with globular granuliferous cells, also bearing (bb) the 

 pores ; c, interstice or mesh of the subdermal reticidated structure 

 or network. 



Fig. 10. The same, portion of the subdermal reticulated structure, greatly 

 magnified, to show that it is composed of elongated fusiform 

 gi'anuliferous cells united into the form of a cord : a a, cord ; 

 6, elongated groups of granules representing elongated fusi- 

 form sponge-cells. 

 Ann. & Mag. N. Hist. Ser.4. Vol.x. 9 



