IX 8 ECHINOIDEA. I. 



in SpIuBrechinus and the small ones in Strongyloccntrotus is a quantitative one, as also the difference 

 between the numerous tubercles in the former and the fewer ones in the latter genus. This, however, 

 does not preclude the fact that especially the deep slits are a character very sharply distinguishing 

 Splurrechinus from Strongylocentrotus. But other characters are found, not quantitative, but structural, 

 which also make a sharp distinction between the two genera, viz. spicules and pedicellarise (comp. the 

 description below of Strongyloccntrotus drobacliicnsis). There can be no question at all of making 

 Sphtrrecliiniis only a subgenus of Strongylocentrotus; it is a very well characterized genus, evidently 

 most closely allied to Psammccliinus, Toxopneustes etc. 



To the genus Pseudobolctia Troschel are, in <Rev. of Ech.» referred the species granulata (Ag.) 

 and Indiana (Mich.); of the latter Prof, de Loriol has kindly sent me a specimen. To the description 

 of this species by Agassiz and de Loriol (245) I can add the following informations. A primary 

 tubercle is found on all the ambulacral plates. The buccal membrane contains, besides the numerous 

 thick plates carrying both spines and pedicellarise, a great number of dumb-bell-shaped spicules and 

 some bihamate ones; inside of the buccal plates numerous small, rather thick fenestrated plates with- 

 out spines or pedicellarise, and a few spicules, most of which are bihamate, almost none of them dumb- 

 bell-shaped. The gills with common fenestrated plates, a few dumb-bell-shaped spicules, and innumer- 

 able bihamate ones. The globiferous pedicellarise as in Splicer echinus; they are strikingly different as 

 to size, but otherwise similarly constructed. The figure given by Agassiz in Challenger >-Echinoidea 

 (PI. XLIV. Fig. 38) is not quite good, as the end-tooth seems there to be constructed quite as the 

 tubular blade; I need scarcely mention that it is constructed in the common way. In the same place 

 is given a rather good figure of a tridentate pedicellaria (Fig. 39), the only objection is that the oblique 

 strise in the blade give a somewhat coarse idea of the little developed net of meshes in the blade. 

 The edge is thick with numerous small teeth, which in the lower part are placed in transverse series, 

 in the outer part irregularly. Ophicephalous and triphyllous pedicellarise of the common form. The 

 stalk compact. In the globiferous pedicellarise numerous spicules are found of about the same form 

 as in Sphcrrechimis; the same form is also found in the tube feet, especially near the sucking disk, 

 together with bihamate spicules that are not branched in the ends. 



According to Agassiz (Rev. of Ech. p. 153) Pseudobolctia macula fa Troschel is synonymous 

 with Ps. Indiana. De Loriol (op. cit.) does not think them to be the same species, and Bell (53) 

 follows this opinion, and maintains farther that Ps. granulata is identical with Indiana. After having 

 examined a couple of specimens of Ps. maculata in British Museum I must also regard maculata as a 

 well distinguished species. The globiferous pedicellarise are as in Indiana, the glands of the stalk are 

 peculiarly lengthened and narrow, almost linear. (Whether this also holds good with regard to Indiana, 

 I am not able to decide by the dried specimen in hand.) The tridentate pedicellarise (PI. XXI. Fig. 1) 

 yield scarcely a sure mark of distinction from Indiana; together with the large form (the head up to 

 i - 5 mm ) where the valves join only in the outer half, a smaller, somewhat different form is found 

 (PL XXI. Fig. 17) where the valves join through their whole length. The ophicephalous pedicellarise 

 (PI. XXI. Fig. 5) are peculiarly elongate with almost straight, finely serrate edge and little developed 

 mesh-work. It is, however, to be observed that on the buccal membrane of Ps. Indiana ophicephalous 

 pedicellarise are found, resembling the figured one rather much, and as I do not remember, and have 



