OF KACHH AND KATTYWAR. 75 



The anterior odd petal and the postero-lateral are equal in length, and the latter 

 is the broader ; the antero-lateral petal is the shortest and narrowest of all, its length 

 being a little less than the odd one, and its breadth also. The ambulacra are slightly 

 tumid and are open distally ; the poriferous zones are broadest midway and are rather 

 pointed towards the ends ; the inner row of pores forms a regular but slight curve, and 

 there is a slight outward turning at the outer extremity. The interporiferous areas are 

 twice the breadth of a poriferous zone. 



Length of odd and posterior ambulacra 23"5 millim. ; length of lateral petals 

 20 millim. ; breadth of odd petal 11 millim. ; of lateral 10 millim. ; of posterior 

 12 millim. 



The variety /3 of M. d'Archiac is pentagonal, longer than broad, broadest on a 

 line with the lateral petals, and narrowest at the truncated posterior angles. The 

 sides are slightly rounded anteriorly and sharply so quite in front ; they are nearly 

 straight, passing backwards and rather inwards behind the point of greatest breadth. 

 The test is thick ; and the slope from the apex is more gradual in front than behind it. 

 The characteristics of the form are the great size of the poriferous zones in the 

 outer third of the petals, the curvature of the line of the inner row of pores, the coni- 

 parative narrowness of the interporiferous areas in relation to the poriferous zones, and 

 the nearly closed condition of the distal ends of the ambulacra. 

 Length of test 71 millim. ; breadth of test 51 millim. 

 Length of odd ambulacrum 21 millim. ; breadth of odd ambulacrum 12*5 millim. 

 „ lateral „ 16 „ „ lateral „ 11"75 „ 



„ posterior „ 21 „ „ posterior „ 12*5 „ 



Interporiferous area 1^ times as broad as the poriferous zone. 

 The odd and postero-lateral petals are thus equal in size and are larger than the 

 antero-lateral. 



This form is specifically distinct from the variety a. 



The third form, Clypeaster Halaensis, d'Archiac, is flat-topped, as is well shown by 

 MM. d'Archiac and Haime {op. cit. plate xiv) ; it is rather thick anteriorly and 

 thin behind, pentagonal, longer than broad, broadest slightly in front with straight 

 sides. The following are the measurements: — Length of test 72"5 millim. (a fracture 

 prevents the breadth being known). 



Length of odd ambulacrum 20 millim. ; breadth of odd ambulacrum 16'5 millim. 

 ,, lateral ,, — ,, ,, lateral ,, XX ,, 



„ posterior „ 20 „ „ posterior „ 12 „ 



The anterior interporiferous area is 1^ times as broad as the poriferous area, 

 and the width of the interporiferous area of the postero-lateral is twice that oi 

 the poriferous zone. The inner line of pores of the anterior ambulacrum is faintly 

 curved, and that of the posterior considerably so ; and all the poriferous zones nearlj 

 approach at their distal ends. 



L 2 



