10 



probably of the size of an apple, were procured west of the Andamans in depths 

 of 4j36 m.= 238 fths. to 531 rQ.=290 fths. Eight young specimens varying in 

 size from a hazel-nut to a walnut and some fragments of larger, hand-high speci- 

 mens were found 13° 27' N., 93° 14' 80" E. in a depth of 741 m.=405 fths. 



Hyalonema J. E. Gray. 



The " Challenger " expedition collected two species of Hyalonema, 

 E. clavigerum F. E. Sch. andif. conus E. E. Sch., in the southern part of the Indian 

 Ocean. The " Investigator " captured quite a number of species of this large 

 and widely distributed genus in the northern part of it. It is possible that the 

 number of species here enumerated will in future be reduced, since, as I have 

 indicated at the time, some of the young specimens described by me more or 

 less provisionally as distinct species may turn out, on more material being avail- 

 able for study, as young stages of other known species. In 1895 I described 

 14 species of Hyalonema collected by the " Investigator, " 6 of these, 

 H. aculeatum, heideri, pirum, heymonsi, weltneri and msehrenthali, I designated at the 

 time as doubtful young forms. Later investigations, the results of which I 

 published in 1899 * showed that H. msehrenthali is a young form of H. affine 

 Marsh. The other 5 of these young, more or less dubious species I will deal 

 with at the end of this chapter, and now describe the 8 good species H. indicum, 

 masoni, lamella, rapa, martabanense, alcorM, investigatoris, and a'ffine, of which 

 fullgrown specimens were examined by me. 



Hyalonema indicum F. E. Sch. 

 Plate III, figs. 1-13 and Plate IV figs. 1-14. 



1895 Hyalonema indicum F. E. Sch. 1894 in Abh. Preuss. Ak. 1894 p. 24, Taf. IV, f. 1-13, Taf. V, f. 1-14. 



The two specimens for which I establish the species Hyalonema indicum are 

 similar in shape and of nearly equal size. They were found in the vicinity of the 

 Laccadives and the Andamans respectively, two localities a considerable distance 

 apart. The slight differences between the Laccadive and the Andaman speci- 

 mens induced me originally to propose the establishment of two distinct species, 

 Hyalonema laccadivense and Hyalonema andamanense for them. They agree in their 

 external form, their structure and their spiculation, to such an extent that I have ' 



decided to place both in one species. I now consider the slight differences be- / 



tween them only sufficient for the establishment of two subspecies, which may 

 perhaps be considered equivalent to so-called varieties. 



I will first give those specific characters which appertain to both specimens 

 and then describe each of the two subspecies for itself. 



* Sitzungsber, der Ges. caturf. Freunde in Berlin 1899 pp. 125-128. 



