101 



pointed out, but it is much less conspicuous; in the latter species also some larger 

 tubercles are found outside the primary one in larger specimens, but this will per- 

 haps also be the case in larger specimens of the new species. In the ambulacra there 

 is a larger secondary tubercle, half as large as the primary one, midway between 

 the inner edge and the primary tubercle; in M. zigzag there is a large tubercle, almost 

 as large as the primary one, rather close to the inner corner of the plate. No pits 

 are visible; neither in M. elegans nor in the specimens examined of M. zigzag were 

 pits to be seen. The apical area is comparatively large (5 mm.), prominent and 

 almost naked; only 2 — 3 small tubercles are found on the middle of each genital 

 plate (in M. zigzag they are almost wholly covered by tubercles). Anal opening 

 central. The buccal membrane contains, besides the usual ring of plates in the 

 oral edge, some small, more or less thorny plates (PI. V. Fig. 17) between and out- 

 side the buccal plates; also the edge of the buccal plates may be somewhat thorny; 

 rather numerous bihamate spicules are also found in the buccal membrane. The 

 spines end in a not very long, central thorn, with a circle of small thorns at its 

 base; the secondary spines are a little widened in the point, the central thorn being 

 little conspicuous. The globiferous pedicellariæ (PI. VI. Figs. 29, 31) are very small 

 and have a rather large lateral tooth; the blade is tlat, not in the usual form of 

 a tube. The valves of the ophicephalous pedicellariæ (PI. VI. Fig. 15) are short and 

 broad, not narrowed in the middle, though not always so short as the figured one. 

 The Iriphyllous pedicellariæ are like those of M. maculatus-, tridentate pedicellariæ 

 are not found. — The colour of the test is pale brownish, the naked spaces being 

 white. The primary spines are white, with a broad red band in the lower part. — 

 For this very distinct species I propose the name Jlicrocypliiis anniilatns n. sp. 



Among some specimens in the British Museum from Port Philip, named Ambly- 

 pneustes ovum (see below) there is a small specimen, which ])robably belongs to this 

 species. The short axis is 7-5 ram., the long 8 mm. (height (5 mm.), the obliquity 

 thus being already rather distinct in this very small specimen — an additional 

 fact tending to show the elongation to be a normal feature of this species. The 

 colour of the test is darker, the naked spaces not white, though paler in colour 

 than the tuberculated part. The red band on the spines is very intense in colour. 

 Otherwise it agrees with the specimen described above. 



Agassiz says (Rev. of Ech. p. 470) with regard to Microcyphiis zigzag „this 

 species is interesting as forming a link between Microcyphiis and Aiiiblypneustes. It 

 has the structural features of the former and the facies of the latter". This is quite 

 true. These two genera are indeed so very closely related that the only real 

 distinguishing character, which seems to be found, is the naked median space in 

 Microcyphus. Now this feature is very slightly developed in M. zigzag (which spe- 

 cies also in form and size is so very like a typical Amblypneiistes), and in Ambly- 

 pneustes there may also be an indication of a bare median space. It will, however, 

 certainly be right to maintain the two genera, which both contain a number of 



