the MorpJiology and Classification of the Saleniidge. 135 



actinal axis may be used, after discovering by his method 

 which is interradium 3 actinally (Loveu, ' Etudes,' p. 47). 



The periproctal ring of Salenia is formed by the basals 

 and the dorso-central plate in the majority of species and in 

 many specimens of some species ; but a radial plate may come 

 in, and it is the radial I. which thus occasionally enters. 

 Usually there is an elevated ridge at the edge of the ring, which 

 is caused by an upward growth of that part of the plates. 

 There may be granules or stunted sessile spines, or even 

 small s])ines on the ring, or it may be plain. The inner edge 

 of the ring gives attachment to the periproctal membrane, and 

 this is penetrated more or less centrally by the anal tube. A 

 series of plates, few in number in the young and more nume- 

 rous in older specimens, covers the membrane, and usually 

 the plates are in irregular circles around the anus, or the ])late3 

 may radiate from the ring to the anus and become smaller 

 and more numerous with age. The plates may carry spinules 

 or small knobs. 



The number of the primary ambulacral tubercles varies 

 with the species, and so does the closeness of the two vertical 

 rows in which they are arranged ; the granulation between 

 the rows differs also in extent and amount. The number of 

 primary plates of the ambulacra is greater in the Mesozoic 

 species than in the Tertiary and recent, except in S. Puttersom, 

 A. Ag., in which the primaries are so crowded that there is 

 doubling of the pairs of pores near the peristome. It is the 

 case that the later Salenice can be classified in a little group 

 by themselves in the genus. 



There is great diversity in the ornamentation of the basals, 

 radials, and dorso-central plate in the species of Salenia, and 

 while it is of a radiating and grooved character in some species 

 it is almost plain in others ; there may be almost a perfect 

 resemblance to the ornamentation of Marsupites, or there may 

 be but a slight radiation of furrows and ridges amongst the 

 other ornamentation, or only spinules may exist fixed without 

 knobs. The sutures of the plates may be just visible, but 

 usually they are distinct and often pitted, and the ornamenta- 

 tion has some reference to the spaces between the shallow pits. 

 Pedicellarise occur on the apical system and elsewhere. 



Genus Salenia, Gray, 1835, amended. 



Test small, subglobose or depressed. Apical system larger 

 than the peristome, more or less raised. The dorso-central plate 

 more or less geometrical, imperfect, and eroded at the right 

 posterior angle by the periproctal ring, in contact with all the 



