AGLAOPHENIA TUBULIFERA. 289 



general resemblance to those of A, pluma, from which, 

 however, they are readily distinguished on examination. 

 The hydrothecae of A. tubulifera are slender, somewhat 

 elongate, gracefully incurved in front, with a very slightly 

 everted margin, and are not expanded above like those of 

 A. pluma, which are also broader and have a very patulous 

 opening. The marginal deuticulation is delicate, and very 

 much finer than in the latter species, in which the rim is 

 cut into large and prominent spines, that are much bent 

 outwards. The lateral nematophores, which in A. pluma 

 are small and inconspicuous, constitute a striking feature 

 in the present species, and give a peculiar aspect to the 

 pinnae when viewed in front. The anterior nematophore 

 in A. pluma is adnate throughout almost the whole of its 

 length, the extremity only being free, and this not pro- 

 jecting much. In A. tubulifera a considerable portion of 

 it is detached and very divergent, and it attains a much 

 greater size, sometimes rising above the rim. 



A very curious and striking character of the present 

 species is the large spur-like process attached to the base 

 of the corbula. This is evidently a supernumerary rib, 

 which, instead of forming part of the protective case, is 

 converted into a mere appendage. The marginal teeth 

 which surround it, and also those which give the serrated 

 appearance to the ribs of the corbula, are all nematophores. 



Hab. On seaweed, zoophytes, shells, &c. in moderately 

 deep water; not common. Off the Isle of Mull in 30 

 fathoms (Prof. E. Forbes): Cormvall, on Goryonia &c. 

 from deep water ; Oban Bay, abundant in 15 to 20 fathoms 

 (T. H.). Very fine and luxuriant specimens were obtained 

 in the last locality, in some of which the plumes were 

 bifid. Hebrides (A.M. N.). 



[There is a specimen from Algoa Bay in Mr. Busk's 

 collection.] 



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