"'l89^'' 1 l'li<>( KKDING.S OF THE NATIONAL MU.SKUM. 207 



tlie dis(!ovoiy of Oravtis, although the Paractinke have been removed 

 froiri tiK'ir liigli place. Two out of three of the genera forming the 

 Tribe Pjotactiniii' are (leei)-sea forms, including uudei- this head all 

 those which liv<? at depths ai)])roa<'hing r>()() fathoms. 



It is «h)ul)tful, however, if any such limitatiou can be set to distinguish 

 dec[)-sea for shallow water forms. What we mean by deep sea forms 

 ari^ forms wlii(;h live under conditions as a rule only to l^e found in tiie 

 deeper water, one of tin' most im[)ortant of which is perhaps great 

 and constant cold. This is a condition which may be o))tained at 

 \arious (lcj)ths according to latitude, and it is quit(i i)ossi))lc, in fact it 

 <locs happen, tliat foinis which in more southern latitudes are found at 

 ;300 to 500 fathoms, may, in higher latitudes, occur at a depth of 30 to 

 50 fathoms. If, howev<'r, a limit is to be given I should suggest one 

 much less than tliat jiroposed by L'lof. Hertwig, j)erhaps as little as 100 

 fathoms. If wonld be better ])robabiy to allow the limit to vary, con- 

 sidering the /,on<i at which the conditions are jiractically constant 

 throughout tiui yeai' to be tlu^ limit of true deej) sea forms. 



There is definite evidence of a wide bathymetrical distribution of 

 deep sea forms. For instance, CoraUiinorphuH profnndun was obtained 

 by the ('hallcnfjrr from 1,375 to 1^,025 fathoms, wliile the. l//>(//ro.s-.v speci- 

 mens were obtained from a depth of only 414 fathoms. So, too, we 

 have seen that Actino.stola callosd ranges from 50 to <Slli fathoms, Acti- 

 naiuje JastujitUi hum 300 to OSO, and A. VcrriUii from 30 to 077. Con- 

 versely also shallow water Ibimsmay extend down to dej>ths sufficient 

 to overlap the regions inhabited by what nmybe considered deep-water 

 forms. For instance, A ntholohd reticulata is tyi)ically a littoral form, 

 yet the C'ludlnif/cf obtained it from a dei»th of 55 fathoms, a depth 

 greater than the highest limit from which either Actinotitola callo,sa or 

 Actinauffe VcrriUii has been dredged. 



Making allowance for such cases, however, it is not difficult to divide 

 the Actiniaria ijito such forms as are typically deep-sea dwellers and 

 those which inhabit shallower waters. Keviewing the various families 

 as to their peculiarities in this iesi)ect, it will be ibund that certain 

 grou[)S may be assigned to one or other category, while others have 

 representatives in Ixjth. Among these latter are the Edwardsi.'e, Pro- 

 tactinia-, Sagartida', l'aiacti(be an<l Corallimori)hida'; among the 

 Sagartiihe the Sagartina; are i»rincipally shallow-water Ibrms, though 

 some such as ^Sagartia lactea and Adamsia ( ?) involvens occur in deep water, 

 while the ( 'houdrVu'tinina', areessentially deep-water fornis, though Fhel- 

 lia hasseveral species dwelling in the littoral zone. The I'aractidie, too, 

 though containing littoral forms are apparently more abundantly rep- 

 resente<l in deep water, and it is interesting to notice that in these as 

 well as in tlie ('hondra<'tinina', the deep-water Ibrms are characterized 

 by the thickniiss and fii'iuness of the mesoghea of the column walls. 

 The liolocerida; so far as known are deep-water forms, as are al-o the 

 genera Poly.stomi(linm, Folijopis, aud ISicyonis; and, on theother hand, the 

 Antheada*, Ibiiiodida'., Phyllactida', Heteractidai, Thalassianthid?e, and 



