232 ACROSALENIA. 



Ammonites oxynotus, Quenstedt, and Ammonites raricostatus, Zieten ; these Ammonites 

 characterise the horizon of this species in a very definite manner. I have lately received 

 the spines of this urchin, which were collected from the Lower Lias near Stratford-on-Avon. 

 Dr. Oppel states that Acrosalenia minuta is found in the Lower Lias of Wurttemberg. 

 " Die flachgedriickten Korper mit den feinen Stacheln fiillen eine ganze Schichte in der 

 Region des Pentacrinus tuberculatus. Sie liegen haufig verkiest in den bituminosen Schiefern 

 des untern Lias an der Steinlach bei Dusslingen, und wurden von meinem Preund 

 Dr. Rolle zuerst darin aufgefunden."* 



History. — First described by Professor Buckman, in the ' Geology of Cheltenham/ as 

 Echinus minutus. Afterwards, in my ' Memoir on Lias Echinodermata,' it was figured for 

 the first time, and described as Acrosalenia crinifera, Quenst.; a comparison of our species 

 with the German urchin has induced me to restore its original specific name. It has been 

 subsequently found by Dr. Rolle in the Tuberculatus bed at Steinlach. 



B. Species from the Inferior Oolite. — 10 e Etage Dajocien, D'Orbigny. 



Acrosalenia Lycettii, Wright. Plate XVI, fig. 1 a, b, c, d, e,f. 



Acrosalenia Lycettii. Wright, Annals and Magazine of Natural History, 2d ser., vol. viii, 



p. 263, pi. 11, fig. 2. 



— — Forbes, in Morris's Catalogue of British Fossils, 2d ed., p. 70. 



— — Desor, Synopsis des Echinides Fossiles, p. 142. 



Test hemispherical, much depressed on the upper surface, and flat at the base ; 

 circumference circular or sub-pentagonal ; ambulacral areas narrow, with two rows of 

 prominent tubercles on the margins ; inter-ambulacral areas wide, the two rows of tubercles 

 with very large, prominent bosses; miliary zone with two rows of granules at the equator, 

 and a naked median depression between the three upper pairs of tubercles ; apical disc 

 small and prominent ; sur-anal plate single ; vent small, and transversely oblong. 



Dimensions. — Height, half an inch ; transverse diameter one inch. 



Description. — This urchin at first sight so much resembles a Hemicidaris that it 

 might readily be mistaken for one, in consequence of the size of the ambulacral, and the 

 prominence of the bosses of the inter-ambulacral tubercles ; but a more careful study of 

 the test soon discloses its true generic character. 



A transmutationist will doubtless find it a difficult matter to discover the progenitor of 

 this urchin ; it makes its appearance in the lowest beds of the Inferior Oolite, with all its 

 Acrosalenian characters so strongly developed, that it may be taken as a good type of the 



* Dr. Oppel, die Jura Formation, p. 110. 



