TH. MORTENSEN, 
26 
(Schwed. Südpolar-Exp. 
Echinocidaris Scythei Philippi. 1857. Neue Echinodermen d. chilenischen Meeres. Arch. f. Naturgesch. 
1857. I. p. 131. 
Arbacia Dufresnii A. Agassiz. 1872 — 74- Revision of Echini, p. 91, 399. 
— — 1874. »Hassler» Echinoidea p. 6. PI. I. Figs. 3 — 4. 
Echinocidaris ( Agarites ) Dufresnii. Troschel. 1873. Die Familie der Echinocidariden. Arch. f. Naturgesch. 
XXXVIII p. 307. XXXIX. 1874. p. 319. 
— alternons. Troschel. 1873. Die Familie der Echinocidariden p. 307, II. p. 323. 
Arbacia Dufresnii. Studer. 1876. Über Echinodermen a. d. antarktischen Meere und zwei neue Seeigel 
von den Papua-Inseln, gesammelt a. d. Reise S. M. S. Gazelle um die Erde. 
Monatsber. d. Berl. Akad. p. 456. 
— alternates. Studer. Ibidem. 
— Dufresnii. Studer. 1880. Übersicht über die während d. Reise S. M. S. Corvette Gazelle um 
die Erde 1874 — 76 gesammelten Echinoiden. Monatsber. Berl. Akad. p. 867. 
Taf. I. Fig. 2. 
Studer. Ibidem. Taf. I. Fig. 3. 
— alternans. 
Echinocidaris Dufresnii. 
Arbacia 
alternons. 
Dufresnii. 
F. Jeffr. Bell. 1881. Account of the Zoological Collections made during the 
survey of H. M. S. ‘Alert’ in the Straits of Magellan and on the Coast of 
Patagonia. IX. Echinodermata. Proc. Zool. Soc. p. 87. 
A. Agassiz. 1881. Challenger-Echinoidea p. 58 (pro parte). 
Lovén. 1887. Echinoidea described by Linnæus. Bih. till K. Svenska Vet.- 
Akad. Handl. Bd. 13. Afd. IV. N:o 5 p. 117. 
Lovén. 1SS7. Ibidem p. 116. 
1895. F. Bernard. Echinides recueillis par l’expédition du Cap Florn (18S2 — 
1883). Bull, du Muséum d’hist. nat. 1895 N:o 7 p, 2. 
1896. M. Meissner. Die von Herrn Dr. Plate aus Chile heimgebrachten See- 
igel. Arch. f. Naturgesch. Jahrg. 62. I. p. 83. 
1900. M. Meissner. Echinoiden d. Hamburger Magalhaensischen Sammelreise p. 5. 
1904. P. de Loriol. Notes pour servir à l’étude des Échinodermes. 2 Ser- 
II. p. 8. PI. II. fig. 2—5. 
1905. C. E. Porter. Los equinidos chilenos del viaje del buque esplorador 
»Challenger» estractados y adicionados de varias notas. Revista chilena. IX- 
p. 131. 
1906. R. Koehler. Stéllérides, Ophiures et Échinides. Expédition antarctique 
Française. Dr. Charcot, p. 29. 
1908. A. Agassiz & Clark. Hawaiian and other Pacific Echini. The Salenidæ, 
Arbaciadæ . . . Diadematidæ. Mem. Mus. Comp. Zool. XXXIV p. 69. PL 47. 
Figs, i — il. 
Non: Echinocidaris africana Troschel. 
This species, so very easily recognizable from its beautiful green colour, has 
been so carefully described in the works quoted, especially by TROSCHEL, LOVÉN 
and DE Loriol, that there is no reason to give a full description of it here again; 
only a few remarks must be given, on account of the question of the specific vali- 
dity of Arbacia alternans , and likewise on account of the new species, A. crassi- 
spina , here distinguished from A. Dufresnii , with which species it has hitherto been 
confounded. 
The shape of the test is rather variable. As seen by the measurements given 
here, the height varies very considerably. Loriol’s statement (Op. cit. p. 9) »test 
Not seen by the author; quoted from Zoological Record 1905. 
