CERIANTHARIA. 



^4 



dition 1908) has no more, notwithstanding that this specimen was considerably larger than other 



specimens with an equally large number of tentacles. The labial tentacles are considerably shorter 



than the marginal. As to the arrangement of the marginal tentacles, that of younger specimens agrees 



with the arrangement indicated by v. Beneden; in older specimens 4 tentacle rings are plainly to 



be seen. Just as in C. membranaccus the 4th cycle is sometimes differently coloured from the other 



three and in the present case the tentacles of the 4th c>-cle are also rather smaller than those of the 



^rd, and lie when fully extended a little outside those of the third cycle. The arrangement of the 



marginal tentacles reckoning from and including the directive chamber, is as follows. 



in younger individuals: 2 (dt) 3, 2, i 3, 2, 3, i 3, 2, 3, i 



in older individuals: 2 (dt) 4, 3, i ! 4, 2, 3, i 4, 2, 3, i 



The tentacles lying nearest the directive tentacle (dt) are in older specimens a little displaced 



outwards. 



The labial tentacles are arranged in 4 cycles according to v. Beneden o dt 3, 2, 4 , 4, i, 3, 2 | 

 4. 3, 1, 2, 4, 3, 1, 2 1 etc. The 8 specimens examined by me shew a rather different arrangement, which 

 has no significance however for the determination of the species, partly because it is ver\- hard to 

 decide to which cvcle the tentacles nearest the directive chamber belong, and partly because the position 

 is variable. I have found the arrangement to be: o J dt 1 4 (3), 2, 3 | 4, i (2), 3, 2 j 4, 3, i, 2 4, 3, t, 2 etc. 

 The arrangement of the labial tentacles then may probably be expressed by the following formula. 



3) 2, 3. 1 

 4, 2, 3, 1 



etc. 

 etc. 



4, 3. 1' 2 



4,3,1,2 etc 



o (dt) 4, 2, 3 j 4, I, 3, 2 



(3) (4) (2) 



In a few specimens examined some tentacles were torn away and regenerated, in others all 

 the top of the column and stomatodaeum was torn away and undergoing regeneration with small, 

 newly formed tentacles. The specimen which Danielssen (1889) has figured, is evidently in the 

 like state. 



The oral disc is of the usual appearance. 



The stomatodaeum is of medium length, faintly furrowed longitudinally, in the most aboral 

 ])art with very deep longitudinal furrow.sT The siphonoglypli is deep, but comparatively small, as, 

 besides the directive mesenteries, only the 2 nearest protomesenteries are attached to the siphonoglypli 

 and that only in the middle portion of it. Only the directive mesenteries are orally and aborally 

 attached to the siphonogiyph. The hyposulcus is small, the hemisulci are distinct and in the lower 

 part resemble filaments. 



Anatomical description. 



The anatomy of this species has been treated by me previously in 1903, but very imperfectly, 

 as I had then only a single and that a badly preserved specimen for examination. I showed how- 

 ever, that the musculature of the mesenteries had an arrangement, which made it extremely likely 

 that the siphonogiyph in the Cerianthidae was not ventral b\it dorsal, and that quite a number of 

 mesenteries went right down to the aboral pole. Afterwards v. Beneden also gave a sketch of the 

 anatomy, though only incidentally. Among other things he has given a sketch of the arrangement 

 of the mesenteries and the grouping of the tentacles (1908, Text-fig. A, p. 25) which in various points 

 however requires supplementing. For, among other things, v. Beneden has not noticed the cnido- 



