192 PROCEEDINGS OF THE AMERICAN ACADEMY 



The most interesting feature of the Echinid^e proper was the oc- 

 currence of several northern forms, E. acutus, E. elegans, and E. 

 norvegicus, in deep water in the tropics. 



Not a single new species of Clypeastroid was found, and the number 

 of specimens even was quite small. They do not play any important 

 part in shaping the character of the fauna of deep water, and are, 

 perhaps, the most strictly littoral group of Echini, indicative, at least 

 in the present epoch, of comparatively shallow water, inside of the 

 hundred-fathom line, and probably giving us a good guide as to the 

 depth of the sea and the nature of the bottom of the cretaceous and 

 tertiary shores, where they occur in such large numbers. 



A recent species of Catopygus ( C. recens, A. Ag.) is interesting as 

 adding another of the cretaceous forms to those still found living. 



By far the most interesting group of Echini collected by the Chal- 

 lenger is the group of Pourtalesle. They were known before only 

 from a couple of genera and a few species collected in the expeditions 

 of the Coast Survey and by the Porcupine. The old material was 

 very limited ; the present material is, in some cases, abundant, and has 

 enabled me to study the affinities of this remarkable group ; j>assing 

 on the one side from Pourtalesia proper to such groups as Aerope, 

 W. Th., and Aceste, W. Th., with the gigantic suckers of their petaloid 

 ambulacra, and on the other, through genera with short anal snouts, as 

 Cionobrissus, A. Ag., and Spatagocystis, A. Ag., to Eckinocrepis, 

 A. Ag., and Calymne, W. Th., in which the resemblance to Infulaster 

 gradually fades, and such genera as Urechinus, A. Ag., and Genico- 

 patagus, A. Ag., appear, reminding us of Holaster, while Cystechinus 

 recalls Ananchytes proper with many features of Micraster. 



Of Pourtalesia, no less than six species are found in the collection, 

 five of which were not among the earlier deep-sea Pourtalesia. 

 (They are P. hispida, A. Ag., P. laguncula, A. Ag., P. rosea, A. Ag., 

 P. ceratopyga, A. Ag., and P. carinata, A. Ag.) 



Of Cionobrissus (C. revinctus, A. Ag.), Spatagocystis (S. Ghal- 

 lengeri, A. Ag.), Eckinocrepis (E. cuneata, A. Ag.), Genicopatagus 

 (G. affinis, A. Ag.), and Urechinus (U. naresianus, A. Ag.), only 

 one species of each genus was brought home. An additional species 

 of Homolampas (H.fulva) shows that the species of this genus grow 

 to a very considerable size. 



A number of specimens of Paleopneustes (P. Murrayi, A. Ag.) 

 were collected near Kagosima, which it may be necessary to place in 

 a separate sub-genus. There are peculiarities in the marginal fascioles 

 and their development, the value of which can only be determined by 



