412 Oy THE ECHIXODERMS OP MACCLESFIELD V, A3TE. [May 1, 



than half an inch in diameter, shows that the form of the test is at 

 first circular rather than decagonal. So far it bears out the remark 

 of Prof . Alex. Agassiz, who, speaking of Peronella orbicularis, says 

 (Eev. Ech. p. 521), " I have but little doubt that this species will 

 prove to be the young of Peronella decagonalis " ; at any rate, the 

 series shows that when sufficiently small specimens are obtained 

 they differ in form from the aduit. "Whether the type of Leske's 

 species corresponds with any one of these I am unable to say. I 

 sent the drawing here reproduced to Prof. Selenka at Erlangen, 

 as I imagined that Leske's type was in the University Museum 

 there *. Dr. Fleischmann, who was kind enough to attend to my 

 letter in Prof. Selenka's absence, says : — " Das Originalexemplar zu 

 Edhinodiscus orbicularis war, wie ich den alten L'atalogen entnehme, 

 niemals in Erlangen. Wie besetzen nur Originalexemplare der 

 Kleins'chen Sammlung." Leske compares his specimen with a 

 Zeeschelling, and Mr. Grueber, of the Department of Coins, who 

 has been kind enough to measure a Zeeschilling for me, tells me it 

 is *65 inch in diameter. The specimen here drawn has about that 

 diameter, but has already ceased to be truly orbicular. 



It is impossible, therefore, to speak certainly, but I think we 

 may safely take it that L, orbiculare is the young of L. deca.'jonale ; 

 this at any rate is certain — a set of specimens collected on 

 Macclesfield Bank form a continuous series, of which the smaller 

 are circular and the larger decagonal in form. 



Abachtstoides placexta. 



Echinus placenta, Linn. Syst. JSat. x. (1758) p. 666. 



Though commonly taken in distinctly southern waters as those 

 of Xew Zealand and Australia, this species has already been 

 recorded from Luzon, and is known as far west as Burmah and 

 Mergui. Not only therefore has it a wide intertropical range, but 

 it is found south of the tropics ; it is to be regretted that on p. 171 

 of the ' Alert ' Eeport I put a sign against the name of this species 

 which indicated that it was not known south of the tropics. 



EXPLANATION OF THE PLATES. 

 Plate XXIII. 

 Fig. 1. Eudiocriims ffranulatus, to show the habit of the species, x 2. 



2. A portion of an arm from above (joints 14-20). X 6. 



3. The most proximal joints of the arm, with their pinnules, X 4. 



4. The seventh pinnule, to show the form and ornamentation of the joints. 



X 12. 



5. One of the most distal pinnules, X 12. 



6. A cirrus. X 4. 



7. The distal joints of a cirrus, X 12. 



Plate XXIV. 

 Fig. 1. Aaiedon bassett-emithi x 2, showing the disc and the bases of the arms 

 with Sz, the first brachial syzygy, varying in position. 



2. Side view of arm of do., X 2. 



3. A cirrus, x 2. 



4. 1st pinnule, to show the form of the joints, X 4. 



5 & 6. 2nd and 3rd pinnules, to show the form of the basal joints, X 8. 



1 See Agassiz, Eev. Ech. p. ix. 



