of Edinburgh, Session 1883-84. 
367 
lower brachials are triangular and sliglitly wider than long ; hut 
they slowly hecome quadrate and finally slightly elongated towards 
the arm-ends. 
The first pair of pinnules (on 2 and 3 hr.) are much longer and 
stouter than the next pair. They reach nearly 15 mm., and consist 
of some thirty smooth joints, the first six of which are short and 
nearly square. The second pair have hut eighteen or twenty 
slender joints, and are only about 6 mm. long. The following 
pinnules increase gradually, both in length and stoutness, reaching 
15 mm, in the outer parts of the arms. The two basal joints 
become slightly flattened and the succeeding ones elongated. They 
have a somewhat glassy aspect, especially in the later pinnules, while 
their ends present the usual dead white appearance. The same 
dilference presents itself in the joints of the younger and more spiny 
cirri round the dorsal pole, and also in the pinnules and cirri of 
Ant. dentata. It recalls the contrast between the hyaline and 
porcellanous types of Fora minif era, though due to entirely dif- 
ferent causes. The ovaries are long and fusiform, extending 
over the greater part of the length of the lower pinnules ; and 
the disc is naked, or rather closely covered with irregular polygonal 
plates. 
Diameter of centrodorsal 5 mm. ; spread about 170 mm. 
H.M.S. “Porcupine,” 1869. Cold area? Two specimens, bear- 
ing seven individuals of Myzostoma cirriferum, F. S. Leuckart. 
Remarks. — The foregoing description is based upon the characters 
presented by three examples of the type, two obtained by the 
“Porcupine” and one by the “Triton.” They all agree very 
closely in their general features, and especially in the curious 
dimorphism of the cirri, which recalls that already noticed in 
Eudiocrinus variansA The shape of the axillaries and of the 
second brachials is very striking, the great length of the former 
being much more marked than in Ant. eschricliti. It is the characters 
of the radials and three lowest brachials which principally dis- 
tinguish Ant. hystrix from Ant. prolixa, Sladen.f Both species are 
remarkable for the small size of the second, as compared with the 
* Journ. Linn. Soc. ZooL, vol. xvi. pp. 496, 497. 
t Duncan and Sladen, A Mem.oir on the Echinoderinata of the Arctic Sea to 
the West of Greenland, p. 77, pi. vi, figs. 7-10. 
