538 H. L. Ilaivkiiis — The Species of Cidnris 



circle is complete, surmounted by thirteen or fourteen secondary 

 tubercles. These are separated from one anotber by spaces often 

 twice as wide as their diameters. They are feebly dev^eloped, often 

 hardly distinguishable from the miliiiries, especially as they are set 

 well back from the rim of the scrobicule. Tliei'e is often a low ridge 

 stretching radially from the rim to the tubercle. Outside the scrobicular 

 circle, but often encroachiug into it, is a complete cycle of tertiai'ies, 

 often guttate in shape, with the prolongation separating the secondaries. 

 There is veiy little difference in size between the secondaries and 

 tertiaries. The miliaries are very small, and only one or two occur 

 on plates of var. typica. They are fairly numerous, but still minute, 

 in var. major. 



Plates from the ambital region are slightly broader than high. 

 The scrobicule is slightly to the adoral side of the centre. Apart 

 from the miliaries, the plates agree in character with those from the 

 upper cycles. The miliary zone is not appreciably increased in 

 importance in var. typica, but in plates of var. major it is quite broad, 

 and the granules are arranged in roughly horizontal lines, starting 

 with the tertiaries, the lines being separated by distinct sulci. This 

 is a very obvious feature, and C. coxiveUenns is one of the earliest 

 species to show the character. Measurements of an average plate 

 from this region are : var. typica, height 7, breadth 7"2 mm. ; 

 var. major, height 9'2, breadth 11 "3 mm. 



As in C. faring donensis, the scrobicule often assumes a slightly 

 elliptical outline near the peristome. The miliaries dwindle in size 

 and numbers until they are practically absent on the adoral plates. 

 The auricles are too poorly preserved to merit description. 



Ambulacral Plates. — There are about nineteen ambulacrals to one 

 interambulacral at the ambitus. The poriferous zone occupies more 

 than half the width of each plate. The pores are separated by 

 a prominent granule. On the non-poriferous pait of each plate is 

 one very prominent granule (not quite reaching the level of the 

 interambulacrals) which is usually accompanied by a much smaller 

 granule on the perradiad margin of the plate. The ambulacra have, 

 therefore, four rows of granules, of which the outer rows are the 

 largest. This applies to the smallest as well as the largest specimens 

 examined. 



The Primary Radiohs. — These are very like tlie radioles of C.pretiom, 

 Desor. They are fairly long, but the length is somewhat counter- 

 balanced by the breadth. Average radioles measure 38 mm. in length, 

 and 5 to 5-5 mm. in greatest breadth. The stem is tumid, especially 

 on one side, and is ornamented by rows of prominent, rounded 

 granules, which are best developed ou the tumid side. There are 

 rarely any rows of granules which do not pass along the entire length 

 of the stem. In some forms the granules are fused into denticulate 

 carinse. At the distal end there is a well - marked corolla. The 

 collerette is very short, and not defined at its junction with the stem. 

 The base is often wider than the broadest part of the stem, and the 

 acetabulum is wide. The rim of the acetabulum is always smooth. 



The Secondary Radioles. — These are very like those described for 

 C. faring donensis, but are always smaller. Those on the holotype 



