20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. ']2 



submerged caves, on piling beneath wharves, and in the irregularities 

 on the outer side of breakwaters; but they are sometimes found 

 among gorgonians or eelgrass, on mangrove roots, and occasionally 

 on mud. 



THE RELATION OF THE COMATULIDS TO TEMPERATURE 



In the recent seas the comatulids range from the very warm water 

 of the tropical littoral to water with a temperature of only 28.7° F., 

 considerably below the freezing point of fresh water. 



The species of the genera of the Oligophreata are especially de- 

 veloped in the warm waters of the present seas, and they are pecu- 

 liarly characteristic of the warm waters of the tropical coasts. The 

 species which occur in this warm water are almost without exception 

 highly specialized, and they are especially remarkable for a great 

 reduplication in the number of their arms, of which they may have as 

 many as 150 or even more, and also for their large size. 



A study of the ontogeny of the most extreme of these types shows 

 that the essential characters of the adults appear at an extraordinarily 

 early age, and also suggests that these characters do not indicate a 

 true phylogenetic progress which will eventually lead to the evolution 

 of new types, but rather a more or less pathological hyperdevelop- 

 ment, an abnormal exaggeration of the normal phylogenetical ten- 

 dencies, which will lead nowhere, but will terminate simply in the 

 extinction of the species in which it appears. The fundamentally 

 aberrant or unbalanced nature of these types is strongly indicated by 

 the invariable conservation of some primitive character, for example 

 spiny borders on the brachials, a regular distribution of the syzygies 

 in the arms, a very primitive type of cirri or of pinnules, etc. 



The species of the genera of the Macrophreata are mostly developed 

 in the colder waters of the recent seas, and this suborder includes all 

 the comatulids of the polar regions and of the abysses. The species 

 which are found in very cold water are almost without exception very 

 primitive, and they are especially remarkable for a reduplication of 

 the radials, a conservation of the carination of the ossicles of the 

 division series and of the arms, a conservation and an exaggeration 

 of the spines which ordinarily are found only among the young, an 

 abnormal shortness of the brachials and of the segments of the 

 pinnules and of the cirri, as well as for their very large and very 

 primitive pentacrinoids in which the radianal plate approaches its 

 original position beneath the right posterior radial ; the greater part 

 of these species are remarkable for their very large size, and they 

 include among their number the largest living crinoids known ; their 



