354 Mr. J. Alder on new species of Sertularian Zoophytes. 



Halecium lahrosum. PI, XIII. 



Polypary between 3 and 4 inches high, irregularly branched 

 and rather flaccid. Stem compounded of several tubes, and 

 fixed at the base by numerous fibres ; the larger branches com- 

 pound and generally dividing dichotomously, bearing alter- 

 nate branchlets or pinnre ; jointed, and more or less ringed or 

 transversely wi'inkled above each joint. The cells arise singly 

 or in pairs below the joints, and are also jointed and ringed at 

 the base, above which a short tubular portion bears the cell, 

 which is moderately deep and much expanded and everted at 

 the margin. Capsules ovate, broad below and obtusely pointed 

 above, without any tubular aperture ; they are of a purplish- 

 brown colour, and set unilaterally on the stem by a short pedicle 

 of about two rings. 



This Halecium has occurred to me occasionally from deep 

 water on the Northumberland coast ; but I have never had an 

 opportunity of seeing it alive. Its distinctness from the other 

 British species, however, cannot be doubted. It diflFers from 

 H. halecinum in its more lax and irregular mode of growth, as 

 well as in colour, which has somewhat of a purplish hue when 

 fresh. The branches, too, are more ringed and wrinkled, and 

 the capsules more regularly and broadly ovate, than in that spe- 

 cies*. But the best distinction is found in the form of the cell, 

 which is deeper than in any of the other species, and has a re- 

 markably expanded lip, which usually turns over at the margin. 

 I may here remark that what Dr. Johnston calls the cell in this 

 genus consists of two portions, the upper and shallower of which 

 constitutes the true cell, and contains the polype. The cells in 

 this species, as in others of the genus, are often seen to rise one 

 within the other, occasioned probably by the polype being re- 

 newed at intervals, and each fresh polype forming a new cell 

 within the old one. 



I have met with what appears to be the young of this species, 

 parasitical on Tubularia indivisa and Sertularia ahietina. In this 

 state it is remarkably delicate and beautiful, and might be taken 

 for a distinct species. The stems rise from a creeping fibre, and 

 arc very strongly and profusely ringed; they give oiF branches 

 from the base of each cell, and sometimes two from one cell. 



A specimen of the adult form, without capsules, has been seut 

 me by Mr. Macdonald of Elgin, obtained in the Moray Frith ; 

 and Mr. Barlee has also met with it lately in Shetland. 



* It has been pointed out by Mr. Hincks, that the male aud female cap- 

 sules are of different forms in H. halecinum. Should this be the ease in 

 other members of the genus, those of H. labrosum now described may 

 belong to the former sex. 



