424 



MU. J. J. SIMI'SON ON THE 



exhibit spiudley beaet witli spiny wart«, of which the simplest 

 are in sixes, eights, or twelves. Some are simple clubs, and 

 pi'obably represent those of the cortical layer. The warts on 

 one side are smaller than those on the other, Tetraradiate 

 forms are ]iot uncommon. The size of the largest spicule is 

 0"18 mm." The only other species referred by him to this 

 genus are I. moniliformis (Steeustrup), I. rjraciUs (Mopaea 

 gracilis), Laraouroux, 



Studer in 1878 established a new species, /. antarctica ; and 

 G. von Koch, in 1887, referred to this genus another form under 

 the name /. neapolitana. 



Wright & Studer, in the ' Challenger' Report, vol. xxxi. 1889, 

 tersely sum up the foregoing characters, and accept Kcilliker's 

 description of the spicules of I. hijijjuris as typical of the genus, 

 placing it in the Family Isidse, Subfamily Isidinse. At the same 

 time the genera Primnoisis and Callisis were added to the 

 classification, and this necessitated the abolition of certain 

 species formerly placed in the genus Isis. 



Thus we see that since the genus was established by Linnteus 

 iu 1737 no I'ewer than nineteen species have been added by 

 various authors, but, stranye to say, only one now remains as an 

 authentic species, viz. I. Idpiniris (Linnaeus). The following 

 table represents these species, the second column iudicatiug 

 their place under the present system of classification and 

 nomenclature : — 



his aiiiareltca, Stud., 1878. 



/. aurantla, Esper, 1797- 



I. capensis, Stud., 1878. 



/. coccinca, E. & S., 1786 ; Gmel. ; 



Esper. 

 /. corcdloidcs, Lamk., 1836; M.-Edw. 



& H., 1857. 

 /. dichoioma, Linu., 1737; Lamk,, 



1836. 

 /. dicho/oiua, Pallas, 1760. 



Mopsella dlcliotoiaa, Gray, 1857. 

 /. clongata, Esper, 1797 ; M.-Edw. & 



H., 1857 ; Lauik., 1836. 

 /. cncrinida, Lamk., 1836. 

 /. crylhracca, Lamk., 1836. 

 I.Jlexihilis, Puurt., 1868. 

 I. c/raciliSjIjSLmk., 1836; Lamx. 

 /. grrgorii, Gray. 1868. 



Friiitnvisls antardka, W. & S., 1889. 

 MclUeea uurciilia. Gray, 1857. 

 Prinbuoisis cdpcn^is. W. & S., 1889. 

 MclitcEa eucviiiea, Gray, 1857. 



Mddla (?) corcdloidcs, Gray, 1857. 



Mojjseu dichufomu, W. & S., 1889. 



McUtodcs dichoioina, W. & S.. 1889. 



Iddclla clongata. Gray, 1857. 



Mopi>ca ciwvinida, Gray, 1857. 

 hidcllco cloitgaia, Gray, 1857. 

 Callisis flcxibllis, W. & S., 1889, 

 Isidella cluiigafa, Gray. 1857. 



