i6 



with the true Japanese Genn. parviis^ a good and detailed description of which has been 

 pubHshed by Mr. Stanley Kemp. 



In his elaborate paper on the Stalk-eyed Crustacea of the West coast of America, Mr. 

 Walter Faxon records an unnamed species of this genus and another unnamed Geiinadas has 

 been mentioned by Miss Rathbun as occurring off the Hawaiian Islands. 



As regards the vertical distribution, it is at present known that all the species of this 

 genus are truly abyssal Penaeidae, usually living at depths, greater than looo m.; from the 

 observations made by several Expeditions Professor Bouvier deduces that these Penaeids usually 

 do not live on or near the bottom of the sea and that their eggs, being lighter than water, 

 rise to the surface. This would explain the fact that young specimens in different degrees of 

 development have often been taken in rather shallow water. 



f 2. Gennadas Pasithea de Man. 



J. G. DE Man, Notes from the Leyden Museum, Vol. XXIX, 1907, p. 146. 



Stat. 230. November 14. 3°58'S., 128° 20' E. Banda Sea. From a depth of 2000 m. to surface 

 I male and i female, both apparently adult. 



This species, in which the i**' — 3'^'^ pereiopods are furnished with a podobranch, really 

 belongs to the genus Gamadas and appears related to Genn. Calniani Kemp from Japan, to 

 Genn. borealis Rathb. from the northwest coast of North America and to Ainalopenaeics elegans 

 S. I. Smith from the Atlantic. 



Male long 41 mm., the female the carapace of which is mutilated, is of a somewhat 

 smaller size. 



The carapace of the male, on which the following description is founded, is 1 2 mm. 

 long, the rostrum included, i. e. two-fifths the length of the abdomen. Except a few setae 

 between the notch at the antero-inferior angle and the carina bounding the antennal groove 

 above, the carapace appears smooth and polished. The slender pointed tip of the lamellar 

 rostrum reaches almost to the middle of ist joint of the antennular peduncle and of the eye- 

 peduncle, whereas in Genn. borealis it reaches sometimes to the cornea. The single, sharp, 

 rostral tooth is situated just above the orbital margin, the gastrofrontal groove runs a little 

 behind that tooth, as in Genn. borealis; post-rostral carina prominent, interrupted both by the 

 cervical and by the post-cervical groove and extending- along the whole length of the carapace. 

 The post-rostral carina is rather sharper in front of the cervical than posterior to the post- 

 cervical groove; the distance between both grooves, measured dorsally, is hardly one- sixth 

 the distance from the post-cervical groove to the posterior margin of the carapace. The gastro- 

 antennal carina that separates the gastric region from the antennal sulcus, is sharp and is 

 produced without interruption to the posterior margin of the carapace ; that part which is 

 situated between the well-cut cervical groove and the post-cervical groove is slightly curved 

 and obtuse, while the posterior part, the cardiaco-branchial ridge, is also obtuse and directed 

 obliquely downward. Branchiostegal spine small, the branchiostegal carina runs at first upward 

 and then curves backward and downward towards the middle of the lower margin of the 



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