58 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



Comatulides (see Part 3, page 400), which is a very generalized type with little resem- 

 blance to other comasterids, and Comatonia (see Part 3, page 288), still more general- 

 ized, with a rounded conical centrodorsal, cirri in 3-4 irregular rows, strong synarthrial 

 backward projections, and sacculi, he relegated to the Macrophreata, hi spite of its 

 perfectly typical and enormous comasterid combs. 



It is quite true that some of the small species of the Colobometridae present a 

 marked superficial resemblance to the species included in the subfamily Perometrinae. 

 Nevertheless this resemblance is purely superficial, and the members of the two groups 

 are always easily distinguished. The cirri are always thoroughly distinctive and 

 show no tendency to intergrade. This confusion seems to have arisen in part from 

 bis disposition of the genus Clarkometra, which he assigned to the Perometrinae, where- 

 as in reality it is a member of the Colobometridae, with perfectly typical colobometrid 

 cirri. 



The small species in the family Colobometridae bear approximately the same 

 relation to the larger that the species of the genera Comatonia, Microcomatula, and 

 Comatulides do to the larger comasterids. 



Dr. Gislen's work on the fossil comatulids is of outstanding importance, and for 

 the first time these puzzling fossils have been brought into a semblance of order. With 

 all due respect for his excellent work, and for him personally, the author believes that 

 far more detailed knowledge of the recent forms and their comparative structure, 

 growth changes, life histories, etc., is necessary before their relationships with the 

 fossils as a whole can be satisfactorily elucidated. 



FOOD AND FEEDING HABITS 



Gisle'n studied in great detail the feeding habits and the food of several recent 

 crinoids. At the Kristineberg Zoological Station he studied Antedon petasus brought 

 in from the outer parts of the Gullmar Fjord, where the species is found on a shell and 

 gravel bottom at a depth of 30-40 meters. At the biological station of Haegdalen, 

 Trondhjem, he studied Hathrometra tenella var. sarsii and Rhizocrinus lojotensis taken 

 between Leksviken and Tautra on muddy bottom at a depth of 250 meters. 



He found Antedon petasus, which he had had opportunities for studying in aquaria 

 for a long time, at the beginning rather difficult to keep alive. It turned out that the 

 temperature of the tank water supplying the aquaria with water was too high (16- 

 18 C.). It was not practicable to use water brought up from the bottom directly, 

 for as this cold water warmed up gas bubbles adhered to the pinnules of the crinoids, 

 which floated to the surface and soon died. This was prevented by setting the ves- 

 sel containing the animals on ice. Afterward by setting the aquarium, filled with 

 water of very high salinity from the outer parts of the archipelago, in a tub filled 

 with ice water he was able to keep Antedon alive and vigorous for weeks. The water 

 did not need changing more than once every, or every other, week. The salinity of 

 the sea water varied between 26 and 28 per thousand. The necessary supply of 

 oxygen was obtained by means of an aerating apparatus of the usual type used at the 

 station. The water was kept at a temperature of 10-12 C. occasionally it was 

 a couple of degrees higher or lower. It was soon found that it was not advisable 

 to let the temperature rise higher than 14 C. With a higher salinity, however, the 

 animals seemed able to stand a somewhat higher temperature. Thus they got on 



