130 SVEN I.OVÉN, ON Til K ECHINOIUEA DESC RIBEl) BY LINNJiUS. 



THiLS, (juoted by Linn.eus for lus E. saxatilis, was lookcd 

 upon by Lamarck as probably inteuded to represeut an Ar- 

 liaeia piinctulata, and by Blainville aud Desmoulins as refe- 

 rable to tho mythical A. loculata Blv., approximations that 

 Troscuel'^) regards as morc tlian donbtful. — Like those of 

 the E. Diadema the ambulacra of thc E. saxatilis present two 

 lateral series of secoudary vernica^, and between tliese not 

 fonr bnt two rows of tertiary verrucula^ In tho young Dia- 

 dema setosura Gray, as wcU as in the adult, there are two 

 rewularlv alternating rows of sparse and miniite but very cou- 

 spicuous tertiary verruc^e, onc such beiug placcd at the su- 

 tural anglc of eacli compound plate. 



The pedicellar geminous pores I uuderstand to be ar- 

 rano;ed in a simple series continiied also ou the under side. 

 In the small specimen of Diadema setosum, the pores dorsally 

 form a nearlv reetilinear series, and ventrally their arches are 

 still all but longitudinal, so as to exhibit a slightly flexuous 

 series, which is doubled only on the hrst two or three plates, 

 ])ut as vet nowhere trebled as in the fullo-rown animal. To 

 tliis juveniie disposition it seems to me that Linn.eus adverts 

 in the words: »Pori duplici serie, subtus etiam obvii» con- 

 trasted with the »obliquis seriebus ex sex poris» of the E. 

 Diadema. 



Each zone of pores is accompanied close on its outside 

 by a series of tertiary verructe said to be »larger», which are 

 »spread» on the under side. The same is said of the E. Dia- 

 dema, where .»sparsa» is replaced by minus ordinata». It has 

 ]»een shown already that this passage would render completely 

 the row of minute interradial verruculje borderiug upon the 

 zone and conspicuous in all the Diadematida?, were it not for 

 that word: »majorum». 1 might suspect the transcriber, only 

 it occurs in both descriptions. 



While in the E. Diadema the interradia present six verti- 

 cal series of verrucaj, the descriptiou gives only four series 

 to the E. saxatilis, and this is their number in speeimens of 

 the Diadema setosum of tlie size of the hgurc A in RuM- 

 THius' book. 



The »verrucce , the primary tubercles, are like those of 

 the E. Diadema; their mamclou is perforatcd. 



') Arch. f. Naturg., XXX VII L p. ;J10. 



