BRITISH FOSSILS. 



Decade IV. Plate III. 



ACROSALENIA DECORATA. 



[Genus ACROSALENIA. Agassiz. (Sub-kingdom Eadiata. Class Echinodermata. 

 Order Echinoidea. Family Echinidse.) Body spheroidal, usually depressed ; ambulacral 

 and interambulacral segments developed, the former bearing two rows of small secondary 

 tubercles, the latter two rows of unequal large primaries ; tubercles perforate and placed 

 on crenulated bosses"; anus excentric, included within the apical disk, which is formed of 

 five genital and five ocular plates, with one or more supplementary plates. Ambulacral 

 avenues with the pairs of pores falling into single file above and on the sides, and becoming 

 distinctly three-ranked near the mouth.] 



Synonyms. Milnia decorata^ Haime, Annales des Sciences Naturelles? 

 3d series, vol. xii., Zoologie, p. 217, plate iii. fig. 1. 2. 3. (1849.) Aero- 

 salenia decorata, Wright, Annals and Mag. of Natural History, 2d series, 

 vol. ix. p. 81. (1851.) 



Diagnosis. A. ambulacris tumidis, tuberculis minutis biseriatim disposifis, 

 remotis ; interambulacrorum tuberculis antero-lateralibus mediocribuSy 

 superioribus minimis, areolis omnium confluentibus. 



In the twelfth volume of the " Annales des Sciences Naturelles,'' 

 M. Jules Haime has described and figured a remarkable Echinite 

 which he had seen in the collection of the British Museum, on 

 the supposition that the specimen in question exhibited characters 

 not met with in any known genus of Sea-Urchins, and that it 

 combined the anal arrangements of the Cassidulidce with the 

 usual characters of the Cidaridce, an union of structures hitherto 

 unobserved. He constituted for it a new genus, Milnea, and as 

 such features prevented its assignment to any family of Sea- 

 Urchins hitherto defined, he made it the type of a new family, 

 which he designated Pseudocidarides. Misled by the sound of the 

 name of the place mentioned as its locality, M. Haime considered 

 it as probably a tertiary species, and from Malta. 



My prejudices led me, in spite of my esteem for the authority and 

 abilities of M. Haime, to doubt the probability of the existence of a 

 combination of characters such as those described and fio-ured : and 

 upon inquiry at the British Museum, my friend Mr. S. P. Woodward, 

 who had shown the specimen in question to its describer, was 

 so kind as to submit it to me for a minute examination. The 

 result is, that the proposed new genus must be cancelled, and that 

 so far from presenting any extraordinary anomalies, tliis urcliin 

 belongs (as Mr. Woodward, indeed, had been aware of before) to 

 the genus Acrosalenia. M. Haime had been misled by the im- 

 [iv. iii.] 4 D 



