55 



trace of a posterior transverse rod was seen; the dorsal arch had been 

 formed. The postero-dorsal rods are fenestrated as the postoral ones. 



In the second culture many of the larvae were more or less abnormal, 

 the body skeleton forming a more or less developed meshwork. 



Mespilia globulus (Linn.). 



PI. VII, Figs. 1—2. 

 Th. Mortenseti. On the development of some Japanese Echinoderms. p. 546. 



Although this speciesi) is fairly common in shallow water near the 

 Biological Station at Misaki, it was quite difficult to get a culture of it, 

 partly because its breeding season appears to be somewhat later in the 

 summer, partly because it was found to be very generally infested with 

 a Trematod living in its genital organs and destroying these more or less 

 completely. I succeeded, however, in getting a fertiUzation of it on June 

 25th 1914, which 

 gave a small, but 

 sufficient number of 

 larvae. They devel- 

 oped quite normally 

 until beginning me- 

 tamorphosis, when 

 the surviving spec- 

 imens had to be pre- 

 served on my depart 

 from the station. 



The developmen- 

 tal processes do not 

 go on so fast as in 

 Temnopleurus toreu- 

 maticus; the embry- 

 os had not yet pas- 

 sed the blastula stage at the age of ca. 24 hours. The young Pluteus 

 does not afford any very marked features; the body is not quite so 

 elongate as in the two other Temnopleurid-larvae described above, and 

 the stomach is not quite so small as in these. Pigmentation is very scarce. 



^) Yoshiwara (Preliminary Notice of new Japanese Echinoids. Annot. Zool. Japonenses. 

 II. 1898, p. 58) has established the species M. levituberculata for the Japanese form of Mespilia. 

 H. L. Clark (Hawaiian and other Pacific Echini. The Pedinidse .... Echinidae, Temno- 

 pleuridse .... Mem. Mus. Comp. Zool. XXXIV. No. 4. 1912, p. 322) maintains that it cannot 

 be separated from the typical M. globulus (L.). On adopting the name M. globulus for it 

 here I must state that it is on the authority of H. L. Clark, having not yet had the opport- 

 unity of critically examining the question myself. 



Fig. 18. Skeleton of larva of Mespilia globulus, 1st stage. 

 A. front view; B. side view. *»%. In flg. B. the postoral rod 

 is abnormally widened into a fenestrated plate; also in fig. A 

 there is a slight abnormity at the base of the right postoral 

 rod. Letters as in fig. 5. 



