i)i) (jaiion A. M. Xovmnn — Notes on the 



and as the posterior rows never have so many lacunas, four- 

 teen may Ije considered the usual full number. 



Hadiata and the species or variety ^w^o??^m«^fl! (PI. IX. fig;. 3, 

 innominata). — In these forms the bars in the youngest state 

 Jiave a pore in the loop, but soon afterwards the lumen-line 

 is raised into a more or less prominent ridge, and the pore is 

 commonly obliterated. The lateral laeunes are generally 

 three or four in number : there are usually no median laeunes, 

 their place being occupied by a longitudinal central rib, 

 which is evident at an early stage of development, and to the 

 sides of Avhich the lumen-ribs commonly afterwards unite 

 themselves. The oral opening is formed much in the same 

 way as in nitido -punctata, but in a more simple manner : the 

 lower bar does not fork as in that species, but its front margin 

 is outspread at the sides until it unites with the oral bar, but 

 leaves in the middle a single large lacune. Tlie form radiaia 

 differs from the innominata which I have just described in 

 having more numerous bars, more numerous laeunes, with a 

 few median laeunes occasionally to be seen; the lumen-ribs are 

 only slight, the longitudinal rib seldom developed. The junc- 

 tion of the oral and suboral ribs, instead of leaving only one 

 large centi al lacune, is indicated by from one to seven laeunes ; 

 though it is seldom that the number is confined to the single 

 lacune characteristic of innominata, and I have only seen such 

 instances of single laeunes in this position in the case of a 

 zooecium here and there in a zoarium. The radiata forms 

 which I have examined are from Birturbuy Bay, Ireland, 

 Guernsey, Naples, and Madeira. A very beautiful form of 

 the variety innominata occurs at Guernsey, all the ribs are 

 very much raised, the central longitudinal rib rises in front to 

 a much elevated process ; but the chief peculiarity consists 

 in spine-formed hollow processes which rise above the base 

 of the lumen-ribs just over the place where in the young is 

 seen the lumen-pore, and from which they doubtless take 

 their origin, I have now described the ordinary cribriline 

 structure in these two forms. But an entirely new feature 

 appears here. Hincks described a '' very delicate setiform 

 appendage " as developed on each side of the lower margiu 

 of the orifice, and in his description of the plate called these 

 organs " vibraeuloid setse,^"" Dr. Harmer has recently C On 

 the Morphology of the Cheilostoma," Quart. Journ. Micr. 

 Sci. vol. xlvi. n. s. 1902, p. 326, pi. xv. fig. 7) traced the 

 matter further, and found these appendages in reduced size 

 present also at regular intervals along the side of the zocecium. 

 Dr. Harmer is of opinion that they not only represent 

 the spines of the aneestrula, Avhich he figures, and that " the 



