232 



DISCOVERY REPORTS 



The outline of the test is almost regularly oval; the height varies rather considerably, 

 as seen from the measurements. Particularly the specimen from St. 170 (no. 5 in the 

 table below) is unusually low. The apical system is central, but the greatest height is 

 behind the apical system, the posterior interambulacrum rising as a more or less 

 prominent keel. The periproct is situated on the slightly truncated posterior end, 

 scarcely visible from below. The labrum is rather prominent, the peristomial part of the 

 test rather conspicuously sunken ; the plastron is quite flat. 



The petals of the male are rather distinctly sunken, the postero-lateral ones more so 

 than the antero-lateral ones. The frontal ambulacrum distinctly petaloid and almost as 

 much sunken as the antero-lateral petals. In the female the paired petals are transformed 

 into deep marsupia, the width of which varies very conspicuously, as seen in Plate IV, 

 figs. 2, 5. 



The interambulacra are more or less raised, the posterior one, as stated, forming a 

 keel, which may be quite sharp or more rounded. The sternum is narrow, gently 

 widening towards the posterior end. The madreporite is small. There are usually three 

 genital openings, but the specimen from St. 170 and one of those from St. 182, both 

 females, have only two. In the former specimen the right anterior marsupium is un- 

 developed (Plate IV, fig. 3) ; this specimen accordingly is somewhat abnormal. 



The spines form a uniform, not very dense covering, among which the numerous, 

 black globiferous pedicellariae in well-preserved specimens stand out very conspicuously 

 on the aboral side. 



The valves of the globiferous pedicellariae terminate in five long, slender teeth, as in 

 Parapneiistes (Plate IX, figs. 22, 23). The rostrate and tridentate pedicellariae also are 

 of the same type as in Parapneiistes, but there is some variation in the shape of the 

 rostrate form (Plate IX, fig. 26). 



The colour is a light brownish. 



The young ones in the same marsupia are in all stages, from the egg to the fully 

 formed young (14 mm.) ready to leave the marsupium. 



In the female holotype the frontal ambulacrum is somewhat abnormally bent 

 (Plate IV, fig. 2). 



This is a very perplexing species. It agrees almost completely in every respect with 

 Parapneiistes reductus, Koehler — but there is no trace of fascicles, whereas the fascicles, 



