248 Observations on SteiyJianoeeros. [":"/Am\ May w*' 



movements indicate disease or age ; its structure is not granular, 

 except at its internal attachment, and is in no way related to the 

 granular layers that occur on each side of it (Fig. 1, Z, I). It 

 presents more the appearance of a cellular structure, but differs 

 essentially from the character of such structure, however much it may 

 on first sight resemble certain vegetable cellulose, the divisions incline 

 to a pentagonal aiTangement, and each junction or union of the 

 fibres is distinguished by a definite nucleated swelling, faintly re- 

 sembling Gratiolet's figures of the nerve cells of the spinal cord 

 (Plate LII., Fig. 8). 



What the ofiice of the projecting processes can be I am at a loss 

 to surmise ; its analogue occui-s in Flvseularia coronetta as a single 

 projection, furnished with a knob at its extremity like a tentacle of 

 Coryne. 



In concluding these remarks I must briefly refer to a point in 

 reference to the case. I find from numerous instances afibrded me 

 in detaching specimens from their support, that the case is not 

 attached to such support around the foot, but to the foot itself; and 

 under such conditions it shows with every retraction of the animal 

 that the tube is so attached, by reason of its being inverted in the 

 manner represented by the dotted hnes (Plate LII., Fig. 1), assuming 

 the foot to be withdrawn to a point {m), which would not happen 

 without some connection with the foot, nor would the outer coating 

 be so drawn in if the case were of the same consistency throughout, 

 for then the retraction of the foot would induce an efi'ect similar to 

 that of " taking a dip" of Canada balsam ; then, taking into account 

 the appearance of the foot itself exhibiting a swelling containing 

 a nucleated body (Fig. 9), which in all probability is a secerning 

 gland for the secretion of the substance of the case, we may con- 

 clude that there is an organic connection between the animal and 

 the case. 



Beyond these minor considerations, we have seen from the fore- 

 going remarks that, notwithstanding the great difterence in external 

 appearance, there exists a very close relationship between these 

 higher and abnormal forms. The trochal disc of Stej^hanocet'os and 

 Floscularia, with theu' accessory processes, are truly the homologues 

 of that of the higher forms with theirs ; they perform precisely the 

 same functions, and this second range of ciha exists, to my certain 

 kno^yledge, in each of the following genera, viz. Melicerta, Limnias, 

 TuhicoJaria, QLscistes, Lacinularia, and Conochilus — in fact in 

 each of the Loricated genera of Ehrenberg ; we have seen that their 

 respiratory system is parallel with, and that on the point of the 

 constancy of the visual organs they are superior to the higher forms, 

 unless future observation prove their constancy to exist in the whole 

 Family ; and we see, moreover, that the manducatory apparatus is 

 of a much higher type than has hitherto been admitted ; and when 



