On the Genus Botellina. 191 



vestibular-like passages to the pinnate outgrowths ; the septa from 

 the inner walls are exposed, as also the foramina, or tubular com- 

 munications to the wall chambers which open out into it, shown in 

 PL XX., figs. 8, 9, 10 and 11, a, b, c. 



The same figures show the wall chambers, by means of micro- 

 photography, of the actual specimens, which are not accidental 

 lacunae, but in a measure regularly constructed ; the sand-grains 

 which form their walls are fixed to each other by a siliceous com- 

 pound, and are arranged in a more or less orderly fashion, so as to 

 form a labyrinth of minute chambers. 



A transverse section across one of the pinnate outgrowths (PL XX., 

 fig. 9) magnified twelve diameters shows the wall chambers more 

 clearly. In this figure the thickness of the walls indicated ; also 

 the fine thin layer of siliceo-ferruginous cement, d, which contains 

 about 2 per cent, of carbonate of lime, and forms the final outer 

 coating of the walls. 



The wall of the primordial cell is chambered in a similar manner 

 to that of the remainder of the test (PI. I., fig. 8b). It possesses one 

 large, or from two to five small pseudopodial (?) openings (figs. 1-3 

 and 7e); oval, or slightly projecting outwards along the edge of its 

 basal portion, which, when living, is most probably buried in the 

 deposit on the sea-fioor, and by which means it is enabled to 

 support or anchor the large, erect, robust test. 



The junction, or neck, connecting the distal portion of the test 

 with the primordial chamber, being the weakest point of the whole 

 structure, will doubtless account for so many imperfect specimens 

 being taken by means of the trawl and dredge, minus the primordial 

 chamber. 



CONCLUDING REMARKS. 



Dr. H. B. Brady, in his description of Botellina labyrinthica, gives 

 its specific name evidently on account, as he states, of the interior 

 of the tube being subdivided irregularly by a labyrinth of coarse 

 sandy particles, except at the rounded terminal cavity (?) which 

 forms an undivided chamber. And, later on, he states that the test 

 has the appearance of a cylindrical tube of a somewhat irregular 

 diameter, one end rather swollen and rounded, the other end always 

 imperfect, apparently broken. At the broad end, the investment is 

 thin and incomplete, and there are many orifices (chambers) * left 

 between the sand-grains ; and this fact, together with the broken 

 condition of the specimens, gives rise to the supposition that when 



* The italics are my own. 



