Il8 ECHINOIDEA. I. 



in Sphærcchinus and the small ones in Strougylocentrottcs is a quantitative one, as also tlie difference 

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

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

 Sphærechinus from Strongylocentrotus. But other characters are fonnd, not quantitative, but structural, 

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

 description below of Strongylocentrotus drobachicnsis). There can be no question at all of making 

 Sphærechinus only a subgenus of Strongylocentrotus^ it is a very well characterized genus, evidently 

 most closely allied to Psammechinus^ Toxopneustcs etc. 



To the genus Pscudobolctia Troschel are, in Rev. of Ech.» referred the species gramilata (Ag.) 

 and iudiaiia (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 foUowing informations. A primary 

 tubercle is fonnd on all the ambulacral piates. The biiccal membrane contains, besides the numerous 

 thick piates carrying both spines and pedicellariæ, a great number of dumb-bell-shaped spicules and 

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

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

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

 able bihamate ones. The globiferous pedicellariæ as in Sphærechhius\ they are strikingly different as 

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

 (PL 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 wa}-. In the same place 

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

 striæ 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 onter part irregularly. Ophicephalous and triphyllous pedicellariæ of the common form. The 

 stalk compact. In the globiferous pedicellariæ numerous spicules are fonnd of about the same form 

 as in Sphærechinus\ the same form is also fonnd 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) Pseudoboletia viaculata Troschel is s)-nonymous 

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

 foUows this opinion, and maintains farther that Ps. granulata is identical with indiana. After having 

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

 well distinguished species. The globiferous pedicellariæ are as in iiidiaita., 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 hånd.) The tridentate pedicellariæ (PI. XXI. Fig. i) 

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

 i'5""") where the valves join only in the onter half, a smaller, somewhat different form is fonnd 

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

 (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 

 pedicellariæ are found, resembling the figured one rather niuch, and as I do not remember, and have 



