960 RECORD OF CURRENT RESEARCHES RELATING TO 



be formed by two ambulacra wbicb lie side by side ; the poriferous 

 zones which touch one another are fused together ; the other zones 

 and the anibiilacral arete are normal in character. In this form the 

 apical system was normal. 



The other specimen is in the collection of the British Museum, 

 and was one of tlie examples of A. fo7-mosus which were brought home 

 by the ' Challenger.' In it no indications of the fifth segment of the 

 corona are to be observed except on the actinal surface, but there are 

 no indications of the interambulacral plates ; just as in Echinus melo, 

 the only other recent species in which a similar abnormality has 

 been noted (Philipiji), it is the left anterior area which has suffered 

 the injury ; the abactinal regions, in these two specimens, differ so far 

 from one another, that in Phillippi's specimen there was a tetramerous 

 arrangement, while in the British Museum specimen all the ten plates 

 are still present ; but this latter differs again from Mr. Stewart's 

 example in having an ocular plate considerably enlarged. Professor 

 Bell imagines that " had its capture been a little delayed, the plates 

 of the fifth segment or area might have been comj^letely forced off." 

 A purely tetramerous test has, he observes, been found fossil ; this, 

 described by H. von Meyer, belonged to the species Cidarites coronatus. 

 The author concluded by insisting (1) on the fact that deviations 

 from the pentamerous type seem, in the Echinida, to be due to abnor- 

 malities, and (2) on the striking constancy which is exhibited by these 

 forms, as compared with Asterids or Ophiurids. 



Remarkable Form of Pedicellaria.* — Mr. Sladen gives in a 

 tabular form the " synonymy " of these organs : — 



O. F. Muller (1778). Valentin (1841). Perrier (1869). 



P. ghhifera = P. gemmiforme = P. cjemmiforme 



P. triphylla = P. opicephale ou huccale = P. ophicephale 



P. tridens — P. tridactyle = P. tridactyle 



In SplicerecMnus granulans the pedicellarife globiferse are very 

 much larger than the rest and are, as compared with the same organs in 

 other Echinids, enormous ; upon their stem or pedicle there is situated, 

 between the middle portion of the shaft and the distal end, a remark- 

 able glandular organ ; it is divided into three separate sacculi, and 

 near the upper portion of each there is a small foramen through 

 which a glairy mucus is extruded ; this extrusion is mostly easily 

 observed when a specimen is placed in fresh water. Each sacculus is, 

 on examination, seen to contain an " elongate-ovate or sub-cordiform 

 mass " ; when seen separately this mass is found to consist of a 

 " white, spongy, reticulated substance with a denser central portion 

 within and a number of moderately large j^ink cells distributed over 

 its surface," external to the general mass. Sections are best made 

 after a preliminary decalcification in a solution of 70 per cent, alcohol 

 with 2 per cent, of hydrochloric acid, and staining in haematoxylin. 

 Transverse sections made through specimens thus prepared show the 

 presence of (1) the epithelial nucleated cells of the investing mem- 



* ' Ann. and Mag. Nat. Hist.,' vi. (1880) p. 101. 



