REPORT ON THE CRINOIDEA. 175 



prolixa and of Antedon tenella in various stages of growth, and the largest cirri that 

 I have met with in the most robust examples of Antedon tenella from the American 

 coast are little more than half as long as those of the "Tegetthoff " specimens of the 

 same size; while the measurements of these last correspond very well with those of the 

 young Antedon prolixa from the Kara Sea and Spitzbergen. 1 Apart from this possi- 

 bility, however, it appears to me that Fischer attributes to Antedon tenella a much greater 

 variability in the size of the cirri than is justified by our knowledge of other Comatulae. 

 He asserts that the small Scandinavian form with cirri 10 mm. long, and consisting of 

 eighteen or twenty joints, which he thinks he got at Jan Mayen, 2 is identical with 

 Sladen's Antedon prolixa which reaches more than twice its size, and has cirri of forty to 

 forty-five joints which reach 60 mm. long. The Scandinavian form is sexually mature and 

 presents all the characters of an adult Comatida ; and if it is only a dwarf variety there 

 must be some reason for its existence. But Fischer believes it to occur at Jan Mayen, 

 side by side with the large form which belongs to the type of Antedon prolixa. This fact, 

 if true, would seem of itself to indicate that the two forms are different ; for if the dwarfing 

 conditions were in operation at Jan Mayen, the large prolixa-tj^e would not exist there. 

 Even if we suppose that the "Tegetthoff" specimens really are a local variety of 

 Antedon tenella with unusually developed cirri, 37 mm. long, of thirty-three joints, 3 there 

 is a great difference between these cirri and those of the mature Antedon prolixa, which 

 may have forty to forty-five joints, and reach 60 mm. in length ; and the difference is 

 still greater if we remember the average size of the cirri in the Scandinavian type. If it 



1 Since the above remarks were printed, Dr. von Marenzeller has been good enough to send me the two 

 "Tegetthoff" specimens for re-examination ; and I have no doubt whatever that they are immature forms of Antedon 

 prolixa, for they agree with this type in all the characters of the cirri, calyx, arms, and pinnules, much better than 

 with either the American or the European variety of Antedon tenella. They were dredged by the "Tegetthoff" in 1873, 

 two years before Sladen's types were obtained by the " Alert," and are therefore the earliest discovered examples of the 

 species. 



2 I have left this discussion almost exactly as it was written originally ; but Dr. von Marenzeller's kindness has 

 recently enabled me to examine the two small specimens from Jan Mayen which Fischer identified with the Scandinavian 

 Antedon sarsii (tenella) ; and I can state without hesitation that they do not belong to this species. It is no doubt the 

 case, as remarked by Fischer, that "Diese zwei exemplaren tragen sammtliche von Diiben & Koren und den 

 spateren Autoren fur Antedon Sarsii angegebenen charakteristischen Merkmale." But Diiben and Koren's description 

 of the type is over forty years old ; and subsequent writers have added little of importance to it. Fischer does not 

 seem to have made a direct comparison of his two small specimens from Jan Mayen with actual examples of the 

 Scandinavian Antedon sarsii, though this would have been by far the most satisfactory way of determining their real 

 nature. Their cirri are considerably larger than those of a Scandinavian form of equal size which has well-developed 

 genital glands and all the other characters of maturity. Its first radials are almost entirely concealed, while in Fischer's 

 specimens a considerable portion of them is visible, very much as in the young Antedon phalangiwm shown on PI. XXVIII. 

 fig. 3. Similar differences appear in the characters of the lower arm-joints of the two forms. In those from Jan Mayen 

 the joints are longer than wide, with incompletely developed pinnules ; while in a Scandinavian Antedon sarsii (tenella) 

 of equal size, these joints are aa wide or wider than long, and present the shape characteristic of the adult individual 

 (PL XXXI. fig. 1). The difference is so marked that Fischer can hardly have overlooked it if he really did compare the 

 two types. But the shape of the arm-joints is not a character to which previous authors have paid much attention ; ami 

 if Fischer simply attempted to identify Antedon sarsii from the published descriptions of it, his reference of the two 

 small forms from Jan Mayen to this type may be readily understood. 



3 See note 1. 



