25 



Hemimenia nov. gen. 



Closely related to Neomenia, from which it differs in the structure of the integument. 

 Leno-th-index 7. Spicula flat, imbricated; no papillae; cuticle thin. Carina with many pouches, 

 filled with large lance-point-shaped spicula. 1 Ventral fold. 1 Pair of vesiculae seminales and 

 1 pair of receptacula seminis. Communication between the precloacal organ and the penis- 

 spicula. No copulation-organ. 



9. Hemimenia intermedia nov. spec. (PI. IV, figs. 118 — 140. PI. V, figs. 141 — 145). 



Stat. 49 ! '. 8°23'.sS., 119 4'. 6 E. Sapeh-strait (between Soembawa and Flores). 69 M. 1 Specimen. 

 Stat. 114. o° 58'. 5 N., 122 55' E. Entrance of Kwandang-Bay, N. Celebes. 75 M. 1 Specimen. 



Length 14 mm. Colóur yellowish-brown. Carina distinct, ] / 16 of the body-height. Number 

 of "Hls 20. 6 — 10 Abdominal spicula on each side. 



2 Specimens from the East-Indian Archipelago. 



The length of the iïrst specimen is 14 mm., the average diameter 2 mm.; the length- 

 index therefore 7. 



The second specimen is too much shrivelled to determine the length-index with any 

 accuracy. 



The animal is pale yellowish-brown and of a silvery brightness (fig. 118). The ventral 

 groove is distinct; the mouth- and cloaca-opening are visible as little round depressions. The 

 ventral part looks like that of Neomenia grandis (Thiele 8, fig. 1 a). A sharply lined carina is 

 present, 0.4 mm. high. Viewed from the dorsal side, it is flat and several round or oval dark 

 spots are distinctly visible (fig. 119). 



The small spicula have a flat spatula-shaped appearance, with strong border; the middle 

 portion is thin ; they are imbricated (fig. 1 20 a, f). Among them there are also found long 

 thin spicula, sometimes bent, often with curved points, but few in number (c, d, e). All along 

 the ventral groove however, they are arranged profusely. On the carina a third form is detected, 

 viz. large, firm lance-pointed spicula (è). These are found at the above mentioned spots on the 

 carina. Such a round spot proves to be a little cavity, entirely filled with these spicula. In Neomenia 

 these spicula are also found in small numbers (cf. Wirén taf. II, figs. 3 — 6), and especially in 

 Neomenia grandis (cf. Thiele 8, fig. 2 a) ; in this species they are only situated on the carina. 



I could not demonstrate any special spicula round the mouth- or the cloaca-opening, as 

 I decalcifiecl the specimens before making the sections. 



The cuticle is thin, as compared with the hypodermis (fig. 121); its thickness never 

 exceeds half of that of the hypodermis; as it is traversed throughout by the very numerous 

 spicula, only a ver)- thin layer remains. The hypodermis on the contrary is thick and appears 

 to me to consist of two layers of cells ; two rows of nuclei are seen one above the other ; 

 sometimes the contour of the cells, clasping each other wedgewise, is visible too, but my sections 

 do not give any positive certainty regarding this point (fig. 121). 



SIBOGA-EXFEDITIE XLVII. 



