I9I4-J S. Kemp : Notes on Crustacea Decapoda. 107 



three pairs consisting of a very short basal portion bearing four 

 large spines two of which are lateral in position. No arthro- 

 branchs at base of peraeopods, epipods present on first four pairs. 



This genus is instituted to receive the very peculiar species 

 described by Nobili under the name of Latrcutes paronae. In the 

 absence of the exopod on the third maxillipede and in the presence 

 of epipods at the base of the peraeopods the genus is intermediate 

 fn position between Latreutes and Tozeutna^ but differs from both 

 in the extraordinary structure of the first peraeopods and in several 

 other characters mentioned in the above diagnosis ; it is most 

 improbable that it has any close genetic relationship with either 

 of these genera. The structure of the second maxillipede is 

 peculiar ; the ultimate segment of the exopod articulates termin- 

 ally with the penultimate^ resembling that found in the primitive 

 families of Caridea. 



Gelastocaris, like several other genera of Hippoh^tidae, 

 shows an extraordinary degree of specialization and, except for 

 the fact that it belongs to the Latreutid section of the family, its 

 affinities are obscure. Judging from its peculiar structure it 

 seems probable that the genus is specially adapted to some 

 unusual mode of life ; but inasmuch as only three specimens are 

 known, regarding none of which are any biological data available, 

 this must remain a matter of conjecture. 



Gelastocaris paronae (NobiH). 

 Plate V, figs, i — ir. 



1905. Latreutes paronae. Nobili, Boll. Mas. Torino. X.\, No. 506, p. 

 2, text-tig. 



The species is of a very robust build ; the carapace, rostrum 

 and abdomen are beset with minute papillae, while on many of the 

 appendages there are delicate featheiy setae. 



The^ carapace (fig i) is not definitely carinate above, but 

 there is a rounded mid-dorsal prominence a little behind the 

 middle and anteriorly, a huge blunt ridge which is highest 

 above the orbital notch and thence rapidly declines to the smooth 

 non-carinate surface of the rostrum. There is no supra-orbital 

 spine, but the anterior margin is produced to a .sharp point 

 defining the lower limit of the orbit and immediately below this 

 point, above the insertion of the antennae, is a sharp outstand- 

 ing post-orbital spine. The antennal spine is very .strong and is 

 flanked by a sharp carina which extends backwards to the middle 

 of the carapace. The antero-lateral portion beneath this carina is 

 flexed inwards on either side, enclosing the first two pairs of 

 maxillipedes. The antero-lateral angle is obtusely rounded ;^ it is 

 not provided with a spine, or, as in Lati^eiitcs, with a series of 

 spinules. In lateral view the inferior margin of the carapace is 

 seen to be excavate posteriorly, leaving the apices of the last four 

 pleurobranchs exposed. 



