'3' 



sion belong to F. vanabilc*^ but a few more nearly approach 

 F. riibrum. In the anatomy of the polyps I can find no 

 constant differences. Semper evidently found few inter- 

 mediates, but such do exist, so that his second species appears 

 to be only a variety. It should be noted that both of Semper's 

 species of Flahellum and his species of Blastotrochus were all 

 found in precisely the same habitat. The latter does not 

 differ except in its so-called generic characters from the two 

 Flahellum. I would hence suggest that here we have a case 

 of three true varieties of a single species with extremely rare 

 intermediates, living together in the same locality, breeding 

 together, but yet the vast majority preserving their parent 

 forms. t 



The species, as above constituted, has been obtained from 

 New Zealand {i^ /,), Bass Straits (38 /.), Phillipines (6-10 /.), 

 China, Singapore ' z--^ f.) and Cape Colony (27-100/".). F. 

 stokesi (= F. variahile Semper;, if regarded as a variety, gives 

 in addition the Arafura Sea '28 and 49 /.) and Maldives 

 (20-50 /.]. In the British Museum I have seen a number of 

 specimens of which six 'close to Nos. i, 2 and 3) were obtained 

 by Captain Sir E. Belcher at the Cape of Good Hope. Of 

 species doubtfully the same F. thoiiarsi comes from the Fallc- 

 land Islands, and F. braziliense Pourtales (Memoirs Mas, 

 Comp. Zooi, Harvard, vol. IV., p. 33] was founded on a single 

 ^^^^ specimen from 40 f. off the Brazil coast. 



6. GENERAL ANATOMY OF THE POLYPS OF 

 F. RUB RUM (Figs. I. and IT). 



Polyp. — The polyp is seated as it were in a cup, formed by 

 the corallite. It lies completely inside the skeleton and doss 

 not extend down in any way on the outside of its walls, 

 forming an edge-zone. lu the expanded condition the polyp 

 would rear itself for at least 5-6 mm. above the epitheca. The 

 tentacles would then be set as in a solitary Actinian round 

 the top of the mouth-disc in a broad, double band separated 

 by the peristome from an elongated stomodoeum. The con- 

 tracted polyp, however, does not rise above its skeletal wall. 



* The proper name of tiiis sp2cie3 or variety should be stokesi, as Mossley has 

 suggested, or soma other of Ed. and H.'s names proposed at the same time. Its 

 synoaym? wjald appear to be F. oivini, aculeitu n, spin^siim, debile, suinitrense 

 and cmieanuTt, all Ed. and H., and F. viridhile Semper. 



Tae oily other living species of Ed. and H. not airealy dealt with is F. o'tt' 

 pressutn (Limirck), of which there can be little doubt F. ajite and F. bxirdi, bath 

 Ed. and H., are synonyms. 



t Such varieties are commDU enough in other groups of the animal kingdom, bat 

 this is the first suggested case in Midreporaria, or, I believe, Coelenterita. The 

 bringing together of the mile and feniile elements is a passive act, so thit it is a 

 fair iaferenee that the three varieties would breed together. 



