ECHINOIDBA. II. 



strongly serrate at the edge (PI. XV. Fig. 35). The sphseridise do not present prominent features; they 

 occur (in the larger specimens) also at the large tubefeet at the posterior end of the test. 



It is an important fact that even in the smallest specimens there is no trace of a latero-anal 

 fasciole, so that it may be regarded as proved that this fascicle is never found in Plemiaster a very 

 characteristic difference from the young of the genus Abatus. In the young Abatus there is a large 

 fasciole enclosing both the apical system and the anal area; a transverse band then develops between 

 the apical and anal area, and the part of the original fasciole behind the transverse band thus 

 becomes the latero-anal fasciole, whereas the anterior part of the original fasciole in connection with 

 the transverse band forms the peripetalous fasciole. In Hemiastcr the anal area is never intrafasciolar. 1 

 In the specimen of 3 mm the peripetalous fasciole is already distinct (Fig. 17), and at a comparatively 

 large distance from the anal area. It is very small and in the anterior petal only one tube-foot is 

 distinct and by no means very large and two more are about to appear. In specimens a little larger 

 the peripetalous fasciole is very prominent, broad, but still enclosing only a very small space (PI. IV. 

 Fig. 10); upon the whole the fasciole is comparatively much broader in the smaller specimens. The 

 odd anterior ambulacrum develops early, thus at a size of 56""" already 4 5 rather large tube-feet 

 are formed. The paired petals are not developed till later on. In a specimen of io mm length I find in 

 the antero-lateral petals 5 pairs of pores in each series, but of the postero-lateral petals no trace is 

 seen as yet. In a specimen 12""" in length I find 2 pairs of pores in each series in the postero-lateral 

 petals. The smallest specimen in which I have found the genital pores developed was 14""" long. 



This species was taken by the Ingolf at the following stations: 



St. 24 (63 06' Lat. N. 56 oo' Long. W. 1199 fathoms 24 C. Bottom temp.) i specimen. 



- 39 (62 oo' 22 38' 865 29 ) 2 



- 40 (62 oo' 21 36' 845 33 ) 8 

 63 (62 40' 19 05' 800 4o ) 2 



- 67 (61 30' 22 30' 975 3o ) 2 



- 68 (62 06' 22 30' 843 3 4 ) i 



- 69 (62 40' 22 17' 589 3 9 ) 3 



Unfortunately several of the , specimens were in a more or less broken condition. - The spe- 

 cies was further taken by the Thor at 62 57' Lat. N. 19 58' Long. W. 975 M. (1903) and by Michael 

 Sars>, 61 40' Lat. N. 3n'Long. E. 220 fathoms, 63 bottom temperature (Ad. Jensen. 1902). The latter 

 locality (the Shetland-Norway ridge) is rather surprising and may indicate the possibility of the species 

 occurring along Norway. (Comp. Echinus Alcxandri). 



The geographical distribution of this species is thus the Northern Atlantic, from the Davis 

 Strait to the Caribbean Sea and from South of Iceland to the Azores. It belongs to the warm 



1 This feature, combined with the ethmophract apical system, the 4 genital pores, the difference in the pedicellarise 

 (evidently the least important character) and the very great difference in the whole shape and appearance, proves beyond 

 doubt that Loven was quite right in maintaining that the antarctic forms: Abalus cavernosus etc. cannot be referred to the 

 genus Ilemiasler, as done by Professor Agassiz. An extraneous form like this, if suffered to remain in the otherwise homo- 

 geneous group of true Hemiasters, is sure to vitiate its integrity, and the mixed assemblage thus set up for a natural genus, 

 if taken on trust, cannot fail to mislead when the question is to trace out comparatively its former geological and actual 

 geographical distribution*. (Loven. On Pourtalesia. p. 73). In his last work, The Panamic Deep-Sea Echini >, Agassiz 

 recognizes the correctness of Loven's views, while Doderlein (Echinoidea d. deutsch. Tiefsee-Exp.) still refers the antarctic 

 forms to Hemiaster, without entering upon the question, however. This question will be treated at more length in my Re- 

 ports on the Echiuoidea of the German and Swedish South-Polar Expeditions). 



