298 TRE ATLANTIC. [chap. v. 



cial interest, for they seemed to be almost the sole inhabitants 

 of red clay from which nearly the whole of the carbonate of 

 lime had been removed. 



The various orders of Crustacea form a most interesting and 

 important element in the ocean fauna. The pedunculated Cir- 

 I'ipedia seem to be universally distributed in comparatively 

 small numbers even at the greatest depths, M'here some of the 

 abyssal sjjecies are larger and more highly ornamented than 

 those previously known from shallow water. Some of the 

 finest additions to our knowledge of species were made among 

 the Schizopoda, in colossal forms of the genera Gnathoj)haiisia 

 and Petalojjhthalmus. 



The macrourous Decapods were very many, and included 

 some splendid undescribed species, especially among the Peneid 

 and Caridid shrimps. There was often, however, some slight 

 doubt whether these forms lived actually on the bottom : we 

 had good evidence that they lived near the bottom, but in sev- 

 eral instances shrimps were captured when we had reason to 

 suspect that the trawl had been buoyed up, and had never act- 

 ually touched the ground. Galathece were frequent to great 

 depths, but brachyourous Decapods appear to be confined al- 

 most entirely to comparatively shallow water. 



The Pycnogonida occurred frequently, and attained an enor- 

 mous size in cold Arctic and Antarctic water at medium depths. 

 The Brachiopoda we found widely distributed, but by no means 

 numerous either as to species or individuals. On one or two 

 occasions, in the Porcicjnne, we got fine hauls of Terebratula 

 cranium and T. septata attached to the pebbles of a gravel of 

 the volcanic rocks of the Faroes, and we took one or two other 

 species with the conditions almost repeated in the neighborhood 

 of the Heard Islands and the Crozets in the Southern Sea. 



The two great modern groups of the Mollusca, the Lamel- 

 libranchiata and the Gastropoda, do not enter largely into the 

 fauna of the deep sea. Species of both groups, usually small 



