VOL. J 



1833 



g'^y'] procep:dings of the nationai> museum. 191 



persisting. It differs liom both the otliers, however, in being utterly 

 devoid of tubercles, tht; only indieatioa of any such structures being the 

 oceurreuc(^ of about t\\ elvc lidges at the upper part of the column, 

 which eud abruptly at the juu<tion of the capitulum aud scapus, but 

 are not tii^ped witli a cuticular thickening. 



The external appearance of these three forms is so dissimilar that 

 one might sup]»ose them to be distinct species. Their occurrence in 

 the same locality, the similarity of their sui)port, in each case a Lamel- 

 libranch shell, and the gradations which tliey show led me to believe 

 that they were identical. T made a detailed study of only one, the 

 second, and cousetpiently can not speak as to the identity throughout 

 of the internal strncture, but so far as this could be examined by slit- 

 ting the sj^ecimens longitinlinally there was jterfect similarity and I 

 have little doubt but that all three ought to be assigned to the same 

 species. 



The infolded capitulum in all the specimens possesses twelve longi- 

 tudinal ridges and, as in Hertwig's Phcllia pcctindta, the ridges towards 

 their u]>per termination are divided by a longitudinal furrow which 

 maybe extensive enough to give the a]>])earance of twenty-four ridges. 

 In the hrst and second ( I'l. xxxii. Fig. IttI) specimens a few tii>ped tuber- 

 cles are found on the infolded ])ortion of the column, resting- in the lower 

 portion of the ridges, and each is more or less distinctly cleft into two 

 parts. The strong si)hincter (PI. xxxii. Fig. 100) has the general appear- 

 ance tigured by Hertwig for I\ pecUnata. In its lower i)art it is thin and 

 composed of cavities which are circular in section, but in its upper part 

 (PI. XXXII, Fig. 101) it thickens somewhat and the cavities are elongated 

 in a direction pcii)endicular to the surface of the mesoghva, some 

 scattered round cavities occurring upon the outer surface of the muscle. 

 I did not fiiul in the mesoglaa of the column wall any of the concre- 

 ments which Hertwig describes in P. peiihiaUt. These seem to have 

 been absent in his P. fipiniferai.iud are probably accidental foreign in- 

 clusions. 



The tentacles (PI. xxxii. Fig. 99,t) are rather short and sh-nder and do 

 not ai>pear to have a bulbous enlargement at the base. They are ar- 

 ranged in about three cycles and appear to number forty-eight. The 

 tirst two cycles correspond to the ridges of the capitulum, regarding 

 each of these as really representing two, while the thir«l cycle tentacles 

 alternate with the ridges. The longitudinal muscles of the tentacles 

 are fairly well develojied and are not imbedded in mesoghea. In color 

 the tentacles seem to haveiesembled the disc, which was of a purplish 

 brown color. Its radiating muscles present the peculiarity already 

 described by Hertwig in P. spmifcra. 



The stomatoda'um is long, reaching to below the middle of the inter- 

 nal cavity (PI. xxxii. Fig. 91), st.), and is of the same purplish brown 

 color which marked the tentacles and di.sc. The broad but shallow 



