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body two rosy, round, irregular-edged plates run from the base of each of 

 the rays, and nearly meet in the centre of the disk, the spaces between 

 being of a soft leathery-like substance, and of a dark brownish colour ; rays 

 and dorsal plates white. — George Sim (Aberdeen). 



Morphology of the TuMNOPLEURiDiE. — The following is an abstract 

 of a communication by Prof. P. M. Duncan, read before the Linnean 

 Society, December 15th, 1881 : — The Temnopleuridee, a subfamily of Oligo- 

 pores, are remarkable for their sutural grooves and depressions at the angles 

 of the plates. The author examined the grooves and depressions, or pits, 

 in Salmacis sulcata, Agass., and found that these last are continued into 

 the test as flask-shaped cavities, sometimes continuous at their bases, which 

 are close to the inside of the test, but do not perforate. This is the case 

 in the median vertical sutures of the interradium and ambulacrum. 

 Between the interradium and the poriferous plates of the ambulacra are 

 numerous pits in vertical series, which are the ends of cylinders closed and 

 often curved within. Altogether the undermining is considerable. The 

 grooves over the sutural margins are losses to the thickness of the test. 

 The edges of the contiguous plates are sutured together by a multitude of 

 knobs and sockets one-eighth of an inch in diameter, visible with a hand 

 lens. In the vertical sutures there is an alternate development of knobs 

 and sockets on each plate, corresponding to a similar development on the 

 opposed plates, and these structures lining the pits. Between the horizontal 

 plate-edges are sutures remarkable in their distinctness and position. The 

 apical edges of the interradial plates have multitudes of sockets, and the 

 actinal edges have, correspondingly, knobs ; whilst the apical edges of the 

 ambulacral plates have knobs, and the actinal ones have sockets. The 

 arobulacrse, on their interradial edge, have nothing but knobs, and the inter- 

 radial plates corresponding sockets ; so that a great series of knobs and 

 sockets (" dowelling ") prevails. Temnopleurus torematicus, Agass., gave 

 similar results, modified by the great development of the grooves, and the 

 young form was shown to differ from the adult, and to have rows of knobs 

 and sockets and barely penetrating pores. The arrangement in Salmacis 

 bicolor and Amblypneustes ovum was considered. The pits have an im- 

 portance, for they increase the superficies of the derm, and near the peristome, 

 as indicated by Loven, they contain Sphmridia. The paucity of knowledge 

 respecting the union of the plates of the Echinoidea was noticed, and the 

 nature of the suturing of an Echinus and Diadema was explained, the first 

 resembling part of that of a young Temnopleurus, but it was without knobs 

 and sockets. The author concluded by separating the Temnopleuridee into 

 two divisions — those with pores, and those with grooves without pores. The 

 last are the oldest in time, and resemble young modern forms, which subse 

 quently develop pits. He reduced the number of genera considerably. 



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