1868.] LOVEN— LESKIA MIRABILIS. 439 



remarkable observations on Sphceronites pomum and Echinospha'- 

 rites aurantium, by means of which Prof. Loven draws the con- 

 clusion that Leskia is a Spatangoid with the mouth of a Cysti- 

 dean, we will give with his own words. (See figures on page 443.) 

 " Good specimens of Sphceronites pomum GylL, collected by 

 Prof. Angelin, show its organization more distinctly than usual. 

 He had observed that this animal had no stalk, but adhered im- 

 mediately to rocks or other objects through a part of its lower 

 surface, which is without pores, and surrounded by a ridge form- 

 ed of the somewhat thickened, free, smooth border of the under- 

 most plates. This surface of attachment is of a very variable 

 form and extension in different specimens, — round and but little 

 excavated in some, oblong and deep in others, — depending upon 

 the nature of the object to which it adhered. On the point 

 opposite to this basal surface lies the apex with the ambulacral 

 apparatus. In the middle of a somewhat deepened area d, through 

 which five delicate but distinct ambulacral furrows pass towards 

 five arms, whose bases form a circle, which however is broken at/*, 

 one-fifth of its circumference. Where the furrows reach the arms, 

 they will be seen to pass into an oblong hole e, which is the lumen 

 of the broken furrow of the lost arm : in every remaining arm- 

 base you will see an indication of the branching of the arms and 

 of the central channels of the branches. Close up to the ambula- 

 cral circle lies the ' pyramid' or mouth a, closed by its five valves 

 of unequal dimensions ; two of them are emarginate on one side 

 in order to give space to the two adjoining outermost arms, 

 which are less than the others, and, as it were, crippled, the right 

 by its vicinity to an oral valve, the left by an apparatus b, that 

 cannot be interpreted otherwise than as an external genital organ. 

 When it is tolerably well preserved, it is conical, with a rounded 

 apex, without any terminal aperture ; for vestiges of valves I have 

 sought in vain, but in two specimens I found the two pores 

 indicated in the figure. From this organ a ridge c runs towards 

 the next arm, suggesting the idea of the possible existence of a 

 ' madreporite.' The centre of the brachial apparatus forms 

 with the genital organ and the oral orifice a compressed but only 

 slightly inequilateral triangle. In Echinosphcerites aurantium 

 the relative position of these parts is the same, but the triangle 

 which they form with each other is much larger, longer, and 

 more inequilateral, because the distances are greater, especially 

 that of the mouth from the ambulacral apparatus, which is cor- 



