6o 



As well in Pen. affinis (H. M.-Edw.) as in Pett. vmtatiis Lanch. (Proc. Zool. Soc. London, 

 1 90 1, PI. XXXIV, Fig. bb, 6c) the petasma has a different form, I wish, however, to remark 

 that the petasma of Pen. monoceros., as it is figured by Alcock (I.e. 1906, PI. Ill, fig. 7^), 

 closely resembles that of Pen. elegans, but in Pen. monoceros the distal posterior lobes are 

 separated from one another by a much larger interspace. 



f 2 1 . Penaeopsis sp. 



Stat. 71. May 10 — June 7. Makassar. Depth up to 32 m. Mud. Sand with mud. Coral. 

 I female. 



I do not succeed in identifying with certainty this specimen, perhaps it may prove to 

 belong to Pen. avirostris (Dana), a species regarded by Col. Alcock as identical with Pen. 

 brevicornis (H. M.-Edw.) (Alcock, Catal. Indian Decap. Crust. Part III. Macrura. Ease. I, Calcutta, 

 1906, p. 22), whereas, according to Nobili, who had the occasion to study six adult specimens 

 from Buntal, on the west coast of Borneo, Pen. avirostris should be a distinct species (Boll. 

 Mus. Torino, N" 447, Vol. XVIII, 1903, p. 2). 



The female from Makassar is 65 mm. long and probably young. The rostrum that 

 reaches to just midway between the end of the antennal scales and that of the antennular 

 peduncle, closely resembles the rostrum of Pett. avirostris (Dana, PI. 40, Fig. 3), the proximal 

 crest, however, is a little less elevated and it bears eight teeth, instead of six. Three 

 teeth are on the carapace, the i^' or epigastric tooth and the smallest of all is almost twice as 

 far distant from the 2^^ as the 2^^ from the 3'''; the 2"^ and following teeth are equidistant; 

 the last tooth is situated at the distal end of the eyes, on the middle of the free part of the 

 rostrum and the slender, styliform, distal part is slightly turned upward. The faint post-rostral 

 ridge disappears not far from the posterior m.argin of the carapace. 



Carapace and abdomen are smooth, but the tomentum is probably worn off, for it is 

 still present in front of the hepatic spine. Orbital tooth small, acute. Antennal spine and hepatic 

 spine of usual size. Gastro-frontal groove distinct and rather deep ; post-antennular groove 

 shallow, anterior part of the cervical groove arcuate and meeting the quite distinct sulcus gastro- 

 hepaticus. As in Pe7i. monoceros, the posterior branchial region is defined superiorly by an 

 oblique ridge, which does not reach to the hepatic sjjine. Antero-inferior angle of the carapace 

 rounded. The i^' — 3'''^ abdominal somites are rounded, the 4'^^ quite inconspicuously carinate 

 on its posterior half; the 6* somite is a little more than twice as long as the 5"^ The telson 

 is a trifle shorter than the 6^'^ somite and considerably shorter than the inner uropod ; longi- 

 tudinal groove deep, lateral margins unarmed. 



The antennular flagella are not complete, they are probably somewhat longer than the 

 two last joints of the peduncle. 



The external maxillipeds hardly reach beyond the end of the antennal peduncle. The 

 three anterior legs are unispinose at base, those of the i^' pair reach to the middle of the 

 antennal peduncle, those of the 3'^'^ almost to the end of the antennal scales, those of the 5"* 

 are short, just extending beyond the end of the antennal peduncles. The coxae of the 4''' 



60 



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