SPINES 39 



about deep-sea fishes before the self-closing dredge 

 came into use. 



One peculiarity of the abysmal fauna, which, to 

 some extent, is a protection against the cavernous 

 jaws mentioned above, is a certain ' spininess ' which 

 has developed even amongst genera that are elsewhere 

 smooth. Such specific names as spinosus, spmi/er, 

 quadrispinosum, are very common in lists of deep-sea 

 animals, and testify to the wide prevalence of this 

 form of defence. A similar spiny character is, how- 

 ever, found in many polar species, even in those of 

 comparatively shallow water; and it may be that this 

 feature is a product of low temperature and not of low 

 level. The same applies to the large size which 

 certain animals attain in the depths. For instance, in 

 the Arctic and Antarctic Seas the isopodous Crustacea, 

 which upon our coasts scarcely surpass an inch in 

 length, grow to nine or ten inches, with bodies as 

 big as moderate-sized lobsters. The gigantic hydroid 

 polyps, e.g., Monocaulus imperator of the Pacific and 

 Indian Oceans, illustrate the same tendency ; and so 

 do the enormous single spicules, several feet long and 

 as thick as one's little finger, of the sponge Mono- 

 rhaphis. Amongst other floating molluscs at great 

 depths, chiefly pteropods, the Valdivia captured a 

 gigantic Carinaria over two feet in length. Of even 

 greater zoological interest were giant specimens of 

 the Appendicularia, vfhich were taken at between i,ioo 

 and 1,200 fathoms. This creature, named by Chun, 

 Bathochordceus charon, reaches a length of about five 

 inches, and has in its tail a notochord as big as a 

 lamprey's. All other genera of this group are minute, 

 almost microscopic. 



There are two other peculiarities common amongst 

 the deep-sea fauna which are difficult to explain. One 

 is a curious inability to form a skeleton of calcareous 

 matter. The bones of many abysmal fishes are de- 



