JOUENAL 



OF THE 



EOYAL MIOROSOOPIOAL SOCIETY. 



OCTOBER 1888. 



TEANSACTIONS OF THE SOCIETY. 



IX. — 'Note on the Reproductive Condition of Orbitolites complanata, 



var. laciniata. 



By Henry B. Brady, F.E.S. 



{Bead 10th Odoher, 1888.) 



Plate X. 



Amongst the Foraminifera that have their home in the shallow waters 

 of the coral-islands of the South Pacific, one of the most remarkable 

 is the large Orbitolite with " crumpled " edges, known as Orhitolites 

 compJr'nata, var. laciniata. It can scarcely be called a common form, 

 in^ ^ uch as its occurrence, so far as at present known, is confined to 

 the Friendly Islands and the Fiji group, though in certain favourable 

 localities it is tolerably abundant. I have never observed it in New 

 Caledonia, where the more typical forms exist in the greatest profusion 

 and specimens of Orhitolites complanata in the normal condition often 

 attain dimensions nearly as great ; nor, so far as I recollect, on the 

 reefs of Samoa. A considerable gathering of the variety referred to 

 was made on the ' Challenger ' expedition, and some of these specimens 



EXPLANATION OF PLATE X. 



Fig. 1. — Orbitolites complanata, var. laciniata, from the Suva reef; 



natural size. 

 ,. 2. — Peripheral view of a portion of the margin, the perforated 



external wall broken away, showing the outer annulus 



crowded with young embryonic shells, corresponding 



to the " primitive discs " of adult normal specimens .. X 15 diam. 

 „ 3. — Transparent horizontal section of the marginal annuli of 



a portion of the shell with embryos in situ X 25 „ 



„ 4,5. — Embryos (" primitive discs "); lateral aspect .. .. x 40 „ 

 „ 6, 7. , one showing a single row 



of apertures, the other two rows ; — peripheral aspect , . x 40 „ 

 „ 8, 9. , horizontal sections, seen 



by transmitted light X 40 „ 



„ 10. — Young specimen, with three annuli of chamberlets, laid 



open to show the interior X 40 „ 



„ 11, 12. — Masses of embryos — horizontal and transverse sections 



— by transmitted light x 40 „ 



„ 13. — Horizontal section of the central portion of an adult 



specimen, by transmitted light X 40 „ 



„ 14. — Transverse section of a similar shell x 40 „ 



1888. 3 B 



