25 



Hemimenia nov. gen. 



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

 Length-inde.K 7. Spicula flat, imbricated; no papillae; cuticle thin. Carina with many pouches, 

 filled with large lance-point-shaped spicula. i \'entral fold, i Pair of vesiculae seminales and 

 I pair of receptacula seminis. Communication between the prccloacal organ and the penis- 

 spicula. Xo copulation-organ. 



9. l/ciiiiiiicnia intermedia nov. spec. (PI. I\', figs. 118 — 140. PI. \, figs. 141 — 145J. 



Stat. 49". 8°23'.5S., 119° 4'.6 I'L Sapeh-strait (between Soembawa and F'lores). 69 M. 1 Specimen. 

 Stat. 114. 0° sS'.5 N., 122° 55' I'-. Entrance of Kwandang-Bay, X. Celebes. 75 M. i Specimen. 



Length 14 mm. Colour yellowish-brown. Carina distinct, \i,; of the body-height. Number 

 of gills 20. 6 — 10 Abdominal spicula on each side. 



2 Specimens from the liast-Indian Archipelago. 



The length of the first 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 an\- 

 accuracy. 



The animal is pale yellowish-brown and of a silvery brightness (fig. i 1 8). 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 (Thielf. 8, fig. i 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 s])icula have a flat spatula-shaped appearance, with strong border; the middle 

 portion is thin; they are imbricated (fig. 120 a, f). Among them there are also found long 

 thin spicula, sometimes bent, often with curved points, but few in number (r, c/^ 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 {6). 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. WiRitx taf. II, figs. 3 — 6), and especially in 

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



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

 I decalcified 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 very 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-EXPEDITIE XLVII, 4 



