On the Classification of the Arthropoda. 55 



Vents sino'le, one at the end of each conical lobe, each pro- 

 vided with a peristome, and all leading to a dilated central 

 cavity or cloaca, whose holes are variable in size and dis- 

 tance apart, corresponding to the breadth of the skeletal 

 layer of this cavity between them ; subcircular, and presenting 

 within respectively from one to three or more openings which 

 belong to the wall-structure. Structure of the wall, which is 

 about l-23rd in. thick, like that of the foregoing species, but 

 with the sagittal radiates still larger. Spicules of two kinds, 

 viz. acerate and triradiate ; no quadriradiates : — 1, aceratcs 

 of two forms, viz. one long, thin, straight, cylindrical, and 

 the other minute, short, and also straig-ht, averaging about 

 14 by ^-GOOOth in.; 2, triradiates, of different sizes and different 

 degrees of irregularity, sagittal and otherwise, the largest 

 averaging 225 by 27-6000ths in., with arms respectively about 

 150 by 8-6090ths in. No. 1 is confined to the peristome in its 

 long thin form, and in its short minute one sparingly to the 

 cribriform sarcode, where it constitutes the mortar-spicule; 

 no. 2, viz. the triradiate, in its smaller form, which is still 

 comparatively large, is confined to the structure of the 

 surface and that of the cloaca, where, in the former, one ray 

 often projects in such a manner that, if not carefully examined, 

 it may be mistaken for a large acerate directed towards the 

 mouth, and the other form, which is much more sagittal, to 

 the wall, where its shafts stretch across this part from opposite 

 sides, and thus overlap each other, while their arms support the 

 skeletal structures of the surface and cloaca. Size of speci- 

 men about i inch in its widest diameter. 



Obs. The chief characters of this specimen are its large 

 triradiates, whose projecting arms on the surface seem to 

 replace the large curved aceratcs usually found there ; also the 

 absence of quadriradiates, and therefore of echinating spines, 

 on the surface of the cloaca. 



[To be continued.] 



VII. — Professor E. Ray Lankester^s Alemoir '' Limulus an 

 Arachnid,^'' and the Pretensions and Charges founded upon 

 it. By Professor Caul Glaus. 

 In a recently published article, in the April number of this 

 Journal, entitled " Professor Glaus and the Glassification of 

 the Arthropoda," Prof. E. Kay Lankester has taken upon 

 himself to bring a series of heavy accusations against me, and 

 asserts that I have borrowed from his Limulus ■vaQraoxx of the 

 year 18S1 the views expressed by me upon the classification 

 of the Arthropoda, on the occasion of a communication upon 

 the heart of the Acarina, which appeared in the ' Anzeiger 



