new Species of Grinuids. 165 



on the dorsal surface of the arm. The separate joints are 

 about *7 millim. in height and 3*2 millim. from the dorsal to 

 the ventral edge. 



The two lowest arm-joints above the axillary radial are sutu- 

 rally united to theinterbrachial plates, and thus bound up with 

 the calyx ; the joints above these appear to have been free, with 

 the exception of the third and fourth, which are connected 

 together by the interaxillary plate. There are from two to 

 three spine-bearing tubercles on each of the arm-joints. 



The pinnules consist of elongate compressed joints, horse- 

 shoe-shaped in transverse section. The longest joint measures 

 "3 millim. and the terminal about 1*8 millim. They are 

 about '5 millim. from the dorsal to the ventral edge. In one 

 or two cases the canals on the ventral surface can be distin- 

 guished. There are apparently six, if not more, joints in 

 each pinnule ; the facets between the joints are smooth and 

 even. The outer surface of the joints is also smooth and free 

 from tubercles. I am unable to determine with accuracy the 

 lowest joint of the arms which is furnished with pinnules, 

 but they appear to commence on the fourth or fifth above the 

 axillary radial. In none of my specimens are there more than 

 eight arm-joints preserved. 



Anal Plate. — This is nearly oblong in form, very slightly 

 wider above than below ; it differs from the first radials, 

 between two of which it is inserted, in not increasing in 

 width to the same extent above and in the absence of the 

 central notch and tumidity (PI. VI. fig. 1, A). Its upper 

 margin is nearly straight and in a line with that of the first 

 radials. The plate varies from 8"5 to 10 millim. in width, 

 and from 10 to 12 millim. in height. 



Anal Interbrachials (PI. VI. fig. 1, lb. A). — The area 

 covered by these plates is nearly half as large again as that 

 in the other interbrachial spaces. In the best-preserved 

 specimens it is 15 millim. in width at the base and at least 

 7*5 millim. in height. There are three vertical zones of 

 plates exposed ; the space above these is concealed from view. 

 In the lowest zone six plates are present ; the two connected 

 with the upper radials on each side are trapezoidal in form, 

 whilst the intermediate four plates are subequal, pentagonal, 

 with straight bases and sides and angular summits. These 

 plates are each about 1'h millim. in width and from 3 to 4 

 millim. in height. Seven plates are present in the second 

 series ; these are polygonal, Avith the lower angles accurately 

 fitting into the angles of the lower series. The upper series 

 is also of seven plates, of a similar character to the series 

 below them. The entire series of plates arc suturally 



