128 Prof. P. M. Duncan on the 



The PediceUarki'. (PI. X[. figs. 23, 24, 25.) 



These beautiful organs occur in vast numbers in Temno- 

 pleurus toreumaticus, but it must be understood that dry tests 

 do not furnish a moderate proportion of those which may- 

 be seen in specimens preserved in alcohol immediately after 

 capture. The reason is that most of all kinds of the pedi- 

 cellaria3 have soft and long or short flexible limp necks, 

 others are placed upon solid stalks. The majority of the soft- 

 necked pediceilariEe fall off in drying and are lost. This 

 can be easily proved by examining dry specimens and col- 

 lecting their pedicellarise, and then comparing the results 

 with the appearances presented by decalcified and coloured 

 parts of the test preserved in balsam. Every pedicellaria of 

 an ambulacrum and of a radial plate can then be preserved, 

 and it is remarkable how they crowd some spots and how 

 long the necks are in relation to tentacles. The very fleshy 

 look of the heads of pedicellaria3 is striking, and so are 

 the muscular developments of many. 



The removal of some of the larger spines is necessary 

 before parts of the test are decalcified, but care must be taken 

 to notice the numerous pedicellaria which are around the 

 scrobicular circles. Some of the pedicellarias are very large, 

 and on the other hand the majority are exceedingly small. 

 Sladen's gland within the body is visible and moderately 

 developed in one grou]i ; but the glandular structure common 

 on the stems of the pedicellariseof some other genera are absent. 



There is no difiiculty in distinguishing four kinds of pedi- 

 cellarige in Temnopleurus. 



1. Large tridactyle forms with a broad base to the body 

 and very long prongs which are moderately broad, arched, 

 becoming slightly narrower and not very sharp-pointed at the 

 free end, being well fenestrated, and having a wide space 

 between the lower parts of the prongs of contiguous valves. 

 The sides of the prongs are slightly dentate, but there are no 

 terminal teeth. 



These largest forms are rare and are seen near the basal 

 plates upon the interradia, and here and there close to an 

 ambulacrum. One or two are upon short stalks, others are 

 upon long and slender ones placed upon small secondary 

 tubercles or upon miliaries, and having muscles at the joint. 

 The most interesting series has a long, soft, transparent neck 

 placed upon a stalk and consisting of a glairy-looking struc- 

 ture, in which a few longitudinally placed muscular fibres, 

 some indefinite granular tissue, and pigment-spots occur. 

 These necks are long or short and limp, and they are found 



