i84 DISCOVERY REPORTS 



The contents of two typical brood-pouches were dissected out. One contained six 

 eggs and six embryos, the other six eggs and eight embryos. The embryos represent 

 many stages in development. The oldest are similar to and of the same size (0-5- 

 0-6 mm. long) as those of /. vivipara having the oral and basal plates in contact with 

 one another (see p. 181). 



The ventral surface of the disk, but not the parts between the arm bases, is plated. 

 In none of the specimens could the nature and arrangement of the plates be completely 

 seen without breaking away the arms and this was done with one small male. In it the 

 disk ambulacra are lined by strong plates. At the apices of two of the interradii there are 

 large plates like orals ; they cannot be seen at the apices of the other three interradii.^ 

 The interradii are occupied by some very large, and other small, plates. In the anal 

 interradius two of the large plates are conspicuous ; one rests on the perisome and the 

 other, in contact and in line with it, rests on the base of the anal cone, on which there 

 are other plates. In nine other specimens some plates can be seen on the disk, as 

 follows : (i) some light plates on the disk ; (ii) and (iii) large plates on the disk ; (iv) and 

 (v) heavy plates along the disk ambulacra ; (vi) what appear to be oral plates ; (vii) a 

 heavily plated anal cone ; (viii) two large plates, one at the base of and one on the anal 

 cone, in contact and in Hne as described above ; (ix) the same and other plates on the anal 

 cone. In the two remaining specimens the arm bases are too firmly pressed together for 

 the disk to be seen. 



Sacculi are numerous, regular and conspicuous on the arms and pinnules of the 

 dusky coloured males ; they are inconspicuous on the other specimens. 



The distal pinnules of some specimens have no ambulacral skeleton, but those of 

 others have reduced side- and cover-plates. The most highly developed are shown in 

 Fig. 16/. The side-plates are reduced to rods which may be simple or forked; the basal 

 parts of the cover-plates are simple stems but the ends of most are spread out fan-wise 

 and are reminiscent of those of the other species of hometra with reduced ambulacral 

 skeletons. The tentacles may or may not contain spicules which may be knobbed or 

 smooth, and scarce or abundant. 



None of the females carries pentacrinoids on its cirri. 



Seven of the specimens were infested with Myzostomum, six on the disk, one on the 

 arms. 



This species may readily be distinguished from the much larger /. hordea by the 

 nature of the oral pinnules and the cirri. It is smaller than /. vivipara, more robust 

 though smaller than the largest specimens of /. graminea. It differs from both in colour, 

 the nature of the pinnules and the degree of thorniness of the brachials and pinnules. 

 It differs from /. vivipara, which has a naked disk, in that its disk is plated ; it differs 

 from /. graminea in having a more heavily plated disk. 



1 See p. 187, under hometra graminea. 



