REPORT ON THE CRINOIDEA. 173 



The non-employment of it by Diiben and Koren in 1844 is not difficult to understand, 

 tor the occurrence of the same specific type on both sides of the Atlantic was not such a 

 familiar idea then as it is now ; and Midler had taken no notice of Asterias tenella, 

 Retzius, in his "Neue Beitriige." These were published in 1843 after his visit to Lund, 

 and contained amended descriptions of Asterias pectinata and Asterias multiradiata, 

 the other two Comatulas mentioned in Eetzius's dissertation, which he had personally 

 examined. Midler's omission to notice Asterias tenella seems to have caused its 

 relegation to the class of species ineertse sedis, from which I am glad to be able to rescue 

 it. I am in some doubt, however, as to whether the " St Croix " of Retzius can be the 

 island Santa Cruz, as mentioned by Gmelin. Retzius did not repeat it in his later 

 dissertation, but simply said " Habitat in oceano Americano." Santa Cruz being a Danish 

 island, one can readily understand that specimens collected there might come into the 

 hands of Swedish naturalists ; but on the other hand it is in latitude 18° N., considerably 

 (about 20°) further south than any locality at which Antedon tenella has been dredged 

 by American naturalists. I have tried, however, but in vain, to identify the Retzian 

 type with any Caribbean Antedon, though it has all the characters of the Scandinavian 

 Antedon sarsii and of Alectro dentata, Say. 



While, therefore, I have no doubt as to its identity with these two types, I should 

 hesitate for the present to quote it as a Caribbean species. 



Remarks. — The Scandinavian variety of Antedon tenella, which was described as 

 Alecto sarsii by Diiben and Koren, is considerably smaller and less robust than individuals 

 dredged from deep water in various parts of the Atlantic. The cirri do not seem to 

 have more than about twenty joints, while there may be six or eight more in 

 individuals from the New England coast, Fseroe Channel, and Kara Sea. The 

 projecting spines at the distal ends of the cirrus-joints are also less developed 

 in the Scandinavian examples. In the larger forms from the West Atlantic the distal 

 ends of the joints in the long oral pinnules are fringed with strong spines, so that they 

 appear to overlap the bases of their successors, and this character is much less developed 

 in the European variety. On the other hand, the delicate calcareous rods at the sides of 

 the ambulacra, which Sars described in the larva, 1 are larger in the Norwegian form than 

 in examples from deeper water ; and they are sometimes entirely absent in the American 

 variety. The latter is also remarkable for the want of constancy in the proportions of 

 its second pair of pinnules. In some examples these have only a dozen joints and are 

 not more than 5 mm. long, but one-third the length of the first pair. But in others 

 they reach 7 or 8 mm. and have as many as twenty joints, a condition which I have 

 not noticed in any individuals from the East Atlantic. 



Antedon tenella is closely allied to two other cold-water species, Antedon hystrix and 

 Antedon prolixa, with both of which it has been found associated. It is distinguished, 



1 Crino'ides vivauts, p. 51, t;il>. vi. tig. 20. 



