from the Island of Malta. 267 



common of all the Maltese Schizastevs, and the one most likely 

 to have been sent to Parkinson, adopted Defrance's identiti- 

 cation. The test is heart-shaped, its widest part being at a 

 line drawn across the disc ; from this imaginary line the back 

 slopes obliquely ft)rwards, and the border is rather bevelled away 

 at the cheeks ; from the same line backwards there rises a pro- 

 minent ridge which bends over into a short tail-like process. The 

 ambulacral areas (3 a) are deeply sunken, the single ambulacrum 

 has a tapering lanceolate form, and the anteal sulcus is deep and 

 narrow ; the poriferous zones lie in the angle of the depression ; 

 they consist of twenty-five pairs of holes, of which the outer 

 series is the largest ; the length of the petaloidal portion of this 

 area from the apex to the fasciole is 1— inch. The antero- 

 lateral ambulacra (3 a) are more divergent in this species than 

 in the other Schizasters met with in the same rocks; they are 

 Ij'o iofii ii^ length and are slightly curved outwards and back- 

 wards ; they make an angle of 35" ; the number of j)ores (3 c) 

 in the zones is respectively thirty-six and thirty-four, the apical 

 eight pairs being almost microscopic : the postero-latcral pair 

 are y^ths of an inch in length and slightly /-shaped ; they are 

 directed backwards at an angle of 65", and are proportionately 

 narrower than the anterior pair ; there are twenty-two pairs of 

 holes in each of the zones, the upper six pairs of which are 

 microscopic. The peripetal fasciole (3 h) is distinctly defined and 

 passes close to the bases of the petaloid portions of the ambu- 

 lacra, but at a short distance from the sides thereof it describes 

 a curve inwards in passing over the anterior interambulacra, and 

 dips obhquely into the anteal sulcus where it unites with that of 

 the opposite side. The lateral fasciole is large and vei-j' distinct; 

 it takes a backward and downward course towards the base of 

 the posterior border, and joins its fellow at some distance be- 

 low the anus ; the two fascioles form the letter V in their trajet 

 on the test. The apical disc is situated very near the centre of 

 the back, removed a little nearer to the posterior than the ante- 

 rior border ; it is perforated w ith four equal-sized genital holes. 

 The anus is oblong, situated high up in the obliquely truncated 

 posterior border, in w^hich is a triangular depression limited on 

 the sides by the fasciole, and above by the anal opening and 

 caudal process ; the base is convex ; the sternum is not very pro- 

 minent, and has lines of tubercles proceeding in radii from a 

 point near the border ; the basal portions of the posterior ambu- 

 lacra are naked, and around the mouth buccal pores are seen 

 which extend at considerable intervals along the trajet of the 

 posterior pair. The mouth is situated in the anterior fourth of 

 the base and has a projecting under-lip ; the basal parts of the 

 interambulacra glide into the general convexitv of the floor of 



