214 UNITED STATES NATIONAL MUSEUM BULLETIN 251 



Figure 96. — Microcosmus exasperatus Heller: a-g. Specimens from Saipan Island: a, right 

 side of 8mm. specimen (USNM 11507); b, left half of mantle body of same specimen, 

 inner side; c, right half of same; d, ciliated groove of same specimen; e, intestinal loop and 

 gonad from 16 mm. specimen;/, right gonad of same specimen; g, ciliated groove of same 

 specimen. A, t, Specimen from Port Jackson: h, left half of mantle body of 17 mm. 

 specimen, inner side; i, right gonad of the same specimen. 



to be unique; even the 13 mm. long Amoy specimen has tentacles with 

 branches in four orders and the 20 mm. long specimen from the same 

 locality boars tentacles with branches in five orders, while the Ifi mm. 

 long Saipan specimen has tentacles with branches in only two ordere 

 and the 17 mm. long Australian specimen has tentacles with branches 

 in three orders. In 19-32 mm, long specimens from the Arafura Sea, 

 described in my previous paper (Tokioka, lOiVi), branches of the ten- 

 tacles were also in only two orders. This feature may be used as a clue 

 to distinguish two groups if it is concluded in the future that two races 

 or forms are recognizable in Microcosmus exasperatus^ after more cru- 



