32 



are irregular, elongated, fenestrated plates, arranged (in the abactinal) in two or 

 (in the aclinal tubet'eet) three or more longitudinal series, Ihe spicules with their 

 axis parallel to the axis of the foot. Sometimes, however, thej' are of Ihe common, 

 triradiate shape. Some few hihamate spicules may also be found. The buccal 

 tubefeet are as usual, provided with large fenestrated plates. 



I ma}' now take the occasion to give some additional remarks on the other 

 Diadematidœ not mentioned above, viz. the genera Centrostephanus, Cœnopedina, 

 Aspidodiadema and Dermatodiadema. As regards Die genus Lissodiadema I must 

 refer to my description of it in Rev. Suisse de Zool. 1903. Vol. XI. p. ;5Ü3, and for Micro- 

 pijga to DE Meijere (Sil)oga-Ech. p. 59). To the description of Micropyga I have only 

 to add a few remarks on the pedicellariæ. The tridentale ones have a well deve- 

 loped meshwork in the bottom of the elongate, rather narrow blade. The edge is 

 coarsely serrate in the lower part, finely serrate with some larger teeth placed in 

 rather regular distances, in the outer part, where the valves join. The small triden- 

 tate pedicellariæ are finely serrate along the whole edge of the blade ( PI. V. 

 Fig. 33, 37). The Iriphyllous pedicellariæ have a distinct coverplate, and the outer 

 edge is extremely finely serrate (visible only under high magnifying powers). (Pi. IX. 

 Fig. 27.) The stalk of the pedicellariæ consists of several very loosely connected rods, 

 being thus very différent from those of the other Diadematids. 



Centrostephanus longispinus. The spicules are triradiate or H-shaped, arran- 

 ged more or less distinctly in mostly four longitudinal series in the lower part of 

 the tubefeet, irregularly in the upper part. In the abactinal tubefeet the spicules 

 are rather numerous, especially towards the point of the foot. In the buccal tube- 

 feet the spicules are large, compact, fenestrated plates. — The pedicellariæ are of 

 four kinds: tridentate, ophicej)halous, globiferous and triphyllous. The tridentate 

 pedicellariæ (comp. Koehi.er: Notes Echinologiques. p. 27. PI. IX. Fig. 10) are verj' 

 elongate, up to almost 3 mm. (head); the neck is rather short. The valves (PI. V. 

 Fig. 29) join in about the outer third part of their length; the blade is narrow, leaf- 

 shaped, with one or a few crossbeams at the lower end, otherwise without mesh- 

 work. The edge is slightly and irregularly serrate in the whole length. Hamann 

 says ' ) that there are two kinds of tridentate pedicellariæ in this species, the one 

 having smaller valves and being „schmächtiger" tiian the other. I have been 

 unable to find more than one form; perhaps it is the otherwise not mentioned 

 triphyllous pedicellaria", which Hamann has taken to be the second form of triden- 

 tale pedicellariæ; he has given no figures of them^). The ophicephalous pedi- 

 cellariæ have a rather long neck and the valves are of the typical structure (PI. IV. 



'; Histologie der Ecliinotlermen. H. .3. p. 15. 



■') Having received from me a preparation of tlic tripliyllous pedicellaria- of Ccnlroslfiihdiiiis 

 longispinus, Prof. Hamann kindly informs me that he thinks lie has confounded the triphyllous pedi- 

 cellariæ with the tridentate ones. 



