HOMOLAMPAS HASTATA. 



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anterior part of the test is quite uniform over the whole actinal side. On 

 the greater part of the interambulacral plates the large secondaries ap- 

 parently run in parallel lines. On the edge and in the angles of the plates 

 the secondaries are arranged on independent parallel lines, Fig. 257. 



The actinal system (PI. 63, fig. 6) is flattened posteriorly ; the actinostome 

 is close to the posterior edge. The anterior part is covered with an outer 

 row of large irregularly polygonal plates, immediately at the actinostome 

 they form a pavement of diminutive plates ; the central part of the actinal 

 system is covered with irregular plates ; the larger plates only carry miliaries. 



The phyllodes extend as far as the third of the anterior ambulacral plates, 

 and are found only on the actinal pair of the posterior lateral ambulacra. 

 The actinal ambulacral plates are bare; the actinal interambulacral plates 



32 mm. 



32 mm. 



32 mm. 



Fig. 257. Homolampas hastata. Fig. 258. Homolampas hastata. Fig. 259. H. hastata. 



(the primordials) carry three to five or six minute secondary tubercles, and 

 all the bare plates round the actinal system are scantily covered by distant 

 miliaries. The actinal region is noted for the length of the labium, which 

 reminds us of that of Linopneustes (PI. 92). 



The structure of the apical system Figs. 258, 259, recalls that of Palaso- 

 tropus (PI. 87, fig. V). The genital plates are ankylosed into a central plate, 

 with four genitals, the madreporic body is found on its posterior part ; the 

 oculars are small but prominent, notched in the central plate (PI. 63, fig. o). 

 Five to six of the abactinal ambulacral plates are perforated by double 

 pores ; they and three or four plates with single pores are enclosed by the 

 peripetalous fasciole PI. 63, fig. 1 ). The stone canal, Fig. 259, extends 

 posteriorly as a ridge nearly twice the length of the central plate (PI. 63, 



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