ECHINOIDEA. I. 177 



Hygrosoma , the difference between the latter and tlie genus Tromikosonia becomes rather more slight 

 than stated in the diagnoses. Then there is only any difference of importance in the form of the tri- 

 dentate pedicellariæ; but this difference is so great, that I, at all events for the present (uutil transi- 

 tional forms become known), must regard the genus Troinikosoma as a legitimate one. 



Kamptosoma asfcn'as (p. 60). All the three specimens from Cliall. st. 272 which Agassiz has 

 determiued as Phonnosoiua touir?^ are K. astcrias. After a renewed examination I must regard it as 

 unjustified to establish a separate species of this genus on them. — It is the primary spines on the 

 actiual side that are flat and widened at the point (PI. XIV. Fig. 29); below they are round, tubular, 

 and then the\- become evenly flattened towards the point. The)' are a little cur\'ed; a hoof is scarceh' 

 found. The spines nearest to the mouth are surrouuded by a rather thick bag of skin , not wideued 

 at the point. The small, accessory ambulacral piates are really wanting, only nearest to the peri- 

 stome a single one ma>- be found. For each ambulacral plate liere are as usual three branches from 

 the radial canals, but two of them are quite thin and their ampullæ rudimentar\', and their tube feet 

 are not developed at all. 



Sperosoiiia Griii/aidii (p. 75). Of this species I have found ca. 20 specimens in the nmseum of 

 Paris (Talisman , the Azores, Morocco, 300 — 1257 m.), determined parth- as Pl/onnoxoina /innnix^ parth- 

 as Astlicnosonia liystrix. Our museum has further received some specimens of different sizes from the 

 Faroe Channel (59° 29' N. L. 7° 51' W. L. 580 — 689 fathoms. Michael Sars . Ad. S. Jensen), a corrob(.)ra- 

 tion of the supposition with regard to its geographical distribution expressed above. — Rather great 

 variation proves to be found in the mutual relation of the size of the abactinal ambulacral piates; 

 accordingly there cannot be laid much stress on the deviations in this respect from the type specimen 

 of Koehler described above, and there can be no doubt that the large specimen figured ou PI. I\'. 

 F'ig. 3, is a real Sp. Gri)iialdii. 



Prionechinus sagittigcr (p. 84). As far as eau be seen on the type specimen preserved in 

 alcohol (st. 218), no grooves are found in the test; to be able to state this faet with certaint>', it will, 

 however, be necessarv to examine a dried specimen. 



Echimts lucidtis (pp. 100, 105) has calcareous piates in the buccal membraue as the other genuine 

 i?r////;?«'-species ; they are simple fenestrated piates as in Er/i. ^Urxai/dn'. There are no spines on the 

 buccal piates (p. 161, note). 



Sterechinus niargaritaccus {^"^.xoi — 102). De Loriol has called m\- attention to the faet that the 

 figures of Ech. margaritaceus given in Voyage de la Frégate Venus . Zoophytes PI. VI. i, do not 

 agree with Koehler's description oi St.antarcticns, especially as all the ocular plates in margaritaceus 

 are shut off from the periproct. Trusting to the interpretation b\- Agassiz of Ech. iiiargaritaccns as 

 the correct one, I had omitted to examine this question more closeh'. According to a kind informa- 

 tion from Dr. (Travier the type specimen is no more found in Paris. But to judge b\- the figures in 

 sVoyage de Venus= there can scarceh- be any doubt that Agassiz's (and my) interpretation of Ech. 

 margaritacetis is incorrect; besides the ocular plates beiug shut off from the periproct, it seems also to 

 appear from these figures that there is a primår)- tuberclc on all the ambulacral plates. But then I 

 do not see how .5"/. inagcllaiiicus is to be distinguished from »largarifacnts^ and it is an obvious sup- 

 position that the)' are realh' one species; if this be the case the name of ii/agellanic/is will onl\- be a 



The Ingolf-Expedition. IV. i. 2, 



