466 



SUPPLEMENT. 



middle : to these processes are articulated two ' trumpets,' whose 

 height is equal to the mouth of the cell. The terminations of the 

 pinnae have four of these trumpets, but, according to my ohserva- 

 tions, the cellules never bear them." F. W. L. Thomas, R. N. 



Family — Campanulariad^. 



Laomedea dichotoma, p. 102. 



"In working up the zoophytes collected by me last summer, 

 (1846,) I have convinced myself of a fact, of which I had previously 

 a strong suspicion, viz., that the margin of the mature cells in Lao- 

 medea dichotoma is always crenulated. The crenulations are shallow 

 (the upper or left hand cells of Van Beneden's figure of C. volubilis 

 are portraits of them.) The crenulations are sixteen, equal to the 

 number of the tentacula in the polype. My specimens are of the 

 normal kind, which abound everywhere in the Firth of Forth. I am 

 well aware of the host of authority against me on this point, and 

 which has made me for a long time dubious ; but the careful exami- 

 nation of hundreds of cells, alive, dried under pressure, and preserved 

 in Goadby's solution, has quite convinced me. I presume that the 

 reason why the crenulations have so long escaped detection, is, that 

 it is difficult to see any margin, for the cells when compared with 

 those of C. volubilis hold the same relation with regard to tenuity 

 that demy does to pasteboard. This is not all connected with them 

 — a horizontal section of the upper half of the cell would not be an 

 even or true circle, but a crenulated one, or in other terms, the upper 

 half is obsoletely ribbed, the ribs or ridges being sixteen in number. 

 — Of the following I am not so positive. This zoophyte was among 



the first which I examined 

 Fig. 82. microscopically, and when 



doing so I witnessed the 

 extrusion of the embryo — 

 Struck with the singularity 

 of the event, of which I had 

 no previous idea, I made a 

 sketch of it upon the margin 

 of your work (by which I 

 was endeavouring to deter- 

 mine the species). I send you a copy of it, (Fig. 82) by which 

 you will see that it differs very much from those figures previously 

 published ; but shipboard is about the worst of places for the micro- 



