REPORT ON THE ECHINOIDEA. 165 



lacral areas. As many of the characters which distinguish. Homolampas fragills from 

 Homolampas fulva are mainly due to age, such as the absence of rudimentaiy petals in 

 Homolamixts fragilis, the small number of very large primary tubercles, the difference in 

 the outline of the subanal fasciole, and the ^jresence of a thread-like peripetalous fasciole, 

 I will make no immediate comparison between them. Homolamjyus /idva is a large species 

 measuring no less than 95 mm. in length. Seen from above the test is elongated, heart- 

 shaped, deeply indented (PI. XXIV. fig. 2) at the odd anterior ambulacrum, with a sharp 

 cut immediately above the anal system (PI. XXIV. fig. 2) in the median interambulacral 

 space. Seen in profile the test is depressed, rises abruptly at the rounded anterior 

 extremity (from the flattened actinal surface) to the rounded apex, which is placed near 

 the anterior extremity, about one-quarter of the distance from the anterior edge of the 

 test to the posterior edge, thence it slopes very gradually towards the posterior extremity, 

 to the abactinal edge of the anal system, which is placed in the anteriorly truncated 

 posterior extremity. The ambulacral areas widen very rapidly from the apical system 

 towards the ambitus, where they attain their greatest width (PI. XXIV. figs. 1, 2, 8). 

 On the abactinal surface the plates of the ambulacral, and of the lower part of the interam- 

 bulacral areas, are covered by minute secondary tubercles and miliaries; the abactinal 

 part of the interambulacra carry, however, a few large primary tubercles entirely out of 

 proportion to the tuberculation of the rest of the abactinal surface. In the lateral 

 anterior ambulacra the anterior row of plates is covered by large secondaries, and the 

 posterior row by small primaries, from the apical system to the ambitus, the same tuber- 

 culation extending on the actinal surface of these zones to the actinostome. On this 

 actinal surface large primary tubercles commencing at the abactinal part of the ambitus, 

 are arranged in a close pavement of uniform size over the whole anterior lateral part of 

 the test, and over the actinal plastron (PI. XXIV. fig. 3). The lateral posterior ambu- 

 lacra with the odd ambulacrum above, are covered with the minute tuberculation so 

 characteristic of the sides of the test above the ambitus. The primary tubercles of the 

 actinal region are surrounded by a large sunken area (PI. XXIV. fig. 9), the intertuber- 

 cular spaces are filled with secondaries. Seen from the interior of the test, the larger 

 tubercular depressions form a pavement of rings more or less perfect (PI. XXIV. fig. 10), 

 much like the pavement of the purses in the interior of Lovenia. The same purses, some- 

 what less developed, are found in the interior of the test below the corresponding primary 

 tubercles of the lateral anterior and posterior ambulacra (PI. XXIV. fig. 8), the sunken 

 areas round these primaries are not so marked as on the actinal surface. The secondary 

 tubercles carry short curved spines, forming a close covering over the whole abactinal 

 surface, from which stand out the gigantic curved spines of the large primary tubercles 

 (PI XXIV. fig. 2). 



On the actinal side the spines of the primary tubercles are somewhat shorter than 

 those of the larger curved spines of the abactinal surface ; they are spathiform and closely 



