ir2 ECHINOIDEA. I. 



otherwise quite brown), there is another fact that may, perhaps, be of some significance. In T. pileolus 

 the secondary tubercles in the ambulacral areas — on the plates wanting the primary tubercle — are 

 as large as the primary ones, so that it can only be seen from their position, whether they are prim- 

 ary or secondary ones; in rosens the primary tubercles are distinctly larger than the secondary ones 

 on the plates where the primary tubercle is wanting. If this feature proves to be constant, there can 

 scarcely be an}- doubt that they are two well distinguished species. In spicules and pedicellarise any 

 difference of importance is scarcely to be found. 



Toxopneustes elegaus Doderl. agrees exactly with T. pileolus (I have not, however, seen the tri- 

 dentate and triphyllous pedicellarise); as far as I can see it is only distinguished from T. pileolus by- 

 its peculiarly coloured spines — they have a sharply limited dark band near the point — and by the 

 colour of the test, it being in T. elegaus yellowish without any indication of coloration, only the median 

 suture of the ambulacral and interambulacral areas is dark violet on the apical side . (Doder- 

 lein 114. p. 99.) 



Toxopneustes variegatus (L,amk). To the existing descriptions I shall add the following 

 remarks. A primary tubercle is found on all the ambulacral plates. The globiferous pedicellarise 

 (PI. XXI. Figs. 38, 40) with tubular blade, without lateral teeth, not very much lengthened. Glands 

 may be found on the stalk, but are most frequently wanting. The tridentate pedicellariae (PI. XXI. 

 Fig. 10) are large, the head up to i'5 mm , and long-necked. There is only little mesh-work in the blade, 

 the edge is straight, rather thick, with numerous, irregularly placed small teeth; the valves are only 

 a little apart below. The triphyllous and ophicephalous pedicellarise of the common form. The 

 spicules (PI. XX Fig. 15) are dumb-bell-shaped, exceedingly numerous in the skin of the globiferous 

 pedicellarise (as in all these species); here all transitional forms may be found from small, oval bodies 

 to typical, bihamate spicules (PI. XXI. Fig. 31), but the really dumb-bell-shaped ones are by far the most 

 numerous. In the tube feet only bihamate spicules are found in small number. 



Toxopneustes semituberculatus (Val.), no doubt, is most nearly allied to T. variegatus; especially 

 must be emphasized that it likewise has a primary tubercle on all the ambulacral plates. Spicules and 

 pedicellarise as in T. variegatus, only the globiferous pedicellarise show a conspicuous peculiarity the 

 lime in the valves being of a deep violet colour, with the exception of a small, oblong, clear spot in 

 the basal part on either side of the apophysis. Glands are found on the stalk. — Otherwise, as is 

 well known, it is distinguished from variegatus by the less marked plate-covering on the buccal 

 membrane. 



Tripneustes esculentus (L,eske). A primary tubercle is only found on every third or fourth 

 ambulacral plate. The buccal membrane contains numerous small fenestrated plates inside of the 

 buccal plates, outside of these fewer, small, round, thick plates with pedicellarise are found. The pedi- 

 cellarise are numerous, much pigmented, and form a quite black ground between the spines. The 

 globiferous pedicellariae are small, the valves as in the other allied forms (PI. XXI. Fig. 39). Glands 

 are found on the stalk. In the tridentate pedicellarise (PI. XXI. Fig. 16) the blade is filled by a highly 

 developed net of meshes; the point rather abruptly widened with the edge exceedingly finely serrate, 

 in the lower part of the blade the edge is more or less coarsely dentate. The valves are rather wide 

 apart, only joining at the point. Together with these a smaller form of tridentate pedicellarise 



