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ECHINOCONUS 



had only one species been so named, but as Klein described three species out of what 

 now appears to be mere varieties of one form in my judgment it is wiser, for the sake of 

 clearnesss and precision, to avoid the revival of either of his names, as it is uncertain to 

 which variety the name globulus should be strictly applied. 



In order to define accurately this species, I have determined to adopt Professor 

 Desor's figures and description as the type retaining the specific name abbreviata without 

 reference to the mould to which it was first applied. 



The test is round, not angular at the border, moderately elevated; convex or 

 subconoidal, a little wider anteriorly, its greatest latitude being across the antero-lateral 

 ambulacra, the sides are unequally inflated, the posterior half being more protuberant 

 than the anterior half, owing to the apical disc being excentral and situated a little forwards 

 (PI. LII, fig. 2 c, PI. LIII, fig. 1) ; the base is flat, the mouth-opening small, round, and 

 prominent ; the vent larger and opening into a recurved prominence formed by the single 

 inter-ambulacrum (PL LII, fig. 2 b, d). 



The ambulacral areas are narrow (PI. LII, fig. 2 e) and built up of a column of 

 small plates, of which four correspond in height to one inter-ambulacral, the outer border 

 of each pair of microscopic pedal plates are united, and in each of these a pair of pores 

 are set obliquely. The anatomy of the pedal plates forming the poriferous zones is more 

 satisfactorily exposed in the specimen npw under examination than I have hitherto seen 

 them, and clearly shows that the poriferous zones are a portion of the test distinct from the 

 plates forming the inter-ambulacra and ambulacra between which they are interposed, each 

 pair of holes being formed, for the passage of the tubular feet, by the growth of a pair 

 of plates around the exertile pedal suckers. 



The inter-ambulacral areas are three times the width of the ambulacral ; on each 

 plate are three horizontal rows of tubercles, four or five in each row (fig. 2 e), each 

 is surrounded by a sunken areola, encircled by granules ; the boss is crenulated, and 

 the summit of the tubercle perforated (fig. 2, g, h). The entire surface of the 

 plates is covered with granules much larger and more numerous than in any other 

 Ecldnoconus. 



The base is flat or slightly concave, and the border rounded ; the single inter- 

 ambulacrum convex, prominent, and recurved at the margin, where the circular vent 

 opens (fig. 2 b, d) ; the mouth-opening is small and central, the peristome feebly 

 diagonal with an elevated border at the circumference. 



The apical disc is small, and its plates so intimately soldered together that few 

 specimens show the sutures (fig. 2 i) ; the disc is excentral and inclined forwards, as the 

 slope from the disc to the anterior border is shorter than the slope from disc to the 

 posterior border; this is owing to the great development of the single inter-ambulacrum 

 and the prominence of the basal portion of that area (see PL LII, fig. 2c; and PL LII, 

 fig. 1). The two pairs of ovarial plates are small, their holes very large (fig. 2 i) ; and the 



