ENCOPE MICHELINI. 329 



in the commencement of the depression of the lunule. The color when 

 alive is dark olive-green. 



The difference in the width of the median ambulacra] spaces is scarcely 

 marked in 3*oung specimens, as is seen by the measurements ; the posterior 

 lunule also is frequently enclosed by the posterior ambulacra in large speci- 

 mens, while in small specimens it is frequently entirely outside the ex- 

 tremity of the petals. The ambulacral petals become more and more dif- 

 ferent in length with increasing size; the difference of the median ambu- 

 lacral spaces is but little perceptible in young specimens. 



Encope Michelini 



! Encope Michelini Agass. 1841. Mon. Scut. 



PL XIP. f. J, ; PL XIP. f. 3, 4 ; PI XII". f. 1. 



The extensive suite of Encopidae brought home by the Thayer Expedition 

 from different points of Brazil, and more particularly the series of all sizes 

 of Encope emarginata which the Museum owes to the kindness of Dr. Fritz 

 Midler, of Desterro, has satisfied me that Liitken is correct in uniting under 

 one name, that of E. emarginata, most of the nominal species he mentions 

 (E. Valenciennesii, subclausa, oblonga, E. quinqueloba), to which we would 

 add the name given by Belval, E. Ghiesbrechtii. Yet I cannot agree with 

 him in referring to the same species Encope Michelini, in which the position 

 of the apex is totally different from that of any of the other species referred 

 to E. emarginata, as is readily seen by the excellent profile given in Agassiz, 

 Mon. d. Scut., PL VP. f. 10. Nor can I agree with him in referring E. grandis 

 to Encope emarginata, a species found in the Gulf of California, and Encope 

 Agassizii, identical with it. There is a second species also found on the West 

 Coast, which Verrill has described as E. occidentals, and which is identical 

 with Encope tetrapora Ac non Gmel. From a careful comparison of speci- 

 mens of E. cyclopora, micropora, and perspectiva, there is no doubt that these 



