30 F. Chapman : 



Mandibular foot with the conical process at its base, charac- 

 teristic of Cypridina as defined by G. O. Sars. Vermifonn limb 

 with about 6 pairs of tine spines towards the extremity, and two 

 long terminal ones. Caudal lamina with about 13 ungues, gradu- 

 ally decreasing in size from the extremity backwards ; the hooks 

 are beset with numerous short spines on the inner surface, to 

 within one-fourth of the tip. Paired eyes large, with about 12 

 lenses seen in the same plane. Muscle impressions situated about 

 the middle of the anterior third, forming a sub-oval cluster of 

 rounded and elongated spots. 



Observatio7is. — The present species is a typical Cypridina, not 

 only because of the presence of the conical pi'ocess at the base of 

 the mandibular foot, but akso on account of the absence of the 

 unguinal process seen in Asterope ; it also shows the blunt, beak- 

 shaped point at the posterior extremity usually possessed by 

 Cypridina. Upon examining living examples of Cypridina 

 thielei under the microscope enclosed in the live-box, they were 

 seen to emit a strong steel-blue light for about 10 minutes, and 

 when the luminosity became faint it could be speedily increased 

 by the application of slight pressure. The heart-pulsations, as 

 observed in some living specimens which had been captured about 

 24 hours previously, and in winter, averaged about 56 per 

 minute. 



The carapace of C. thielei, has a very interesting structure, for 

 most of the valves, when mounted in media and placed between 

 crossed nicols under the microscope^ show various centres of cry- 

 stallization due to the local formation of radial groups of crystals 

 of phosphate of lime. These groups show the usual dark cross of 

 crystals having a straight extinction. This calcification n)ay be 

 seen on the dried valves as opaque white patches. Sorby men- 

 tions this crystalline radial structure which is so eminently 

 developed in crab shells, as occui-ring also in Entomostraca.^ 

 The same structure is also seen, and in a more advanced stage, in 

 the valves of a species of Crossophorus, which Mr. J. H. Gatliff 

 found at Portsea, Port Phillip, Victoria, and kindly favoured 

 me with some short time ajjo. 



1 Quart. Jourii. Geol. Soc, vol. xxxv., 1879, p. 61. 



