TliE GENUS ANASPIDES. 789 



from each other (fig. 2, oc). The appearance of these structures suggests at once that 

 we have here to do with a group of ocelli. We cannot say positively, however, whether 

 this is the case, since an attempt to ascertain by sectioning the structure of the organs 

 was frustrated by the bad state of preservation of our material. There appears, how- 

 ever, to be no lenticular thickening, but rather a thinning away of the chitinous cuticle 

 over the central spot, while the small lateral spots correspond to pits or actual perfora- 

 tions of the cuticle, and may possibly be merely the points of insertion of setEe which 

 have been destroyed in the specimens examined. Whatever may be the nature of these 

 or of the central spot, whether they be ocelli, as their appearance suggests, or not, we 

 know of no structure in any adult Malacostracan with which they are comparable. Their 

 position corresponds roughly with that of the " neck gland " of the Phyllopods, which 

 has been identified with the embryonic " dorsal organ " of certain Malacostraca (Edri- 

 ophthalmata, Mysidse, &c), but in the absence of further information as to their struc- 

 ture, it is impossible to guess what the meaning of these remarkable " ocelli " may be. 



Antennules. — We have little to add to Mr Thomson's description of these organs. 

 We can confirm his account of the auditory organ which is lodged in the first joint of 

 the antennule and opens to the exterior by a narrow slit on the upper surface near the 

 anterior end of the joint (fig. 2, e). The possession of an auditory sac in this position 

 has hitherto been regarded as characteristic of the Decapoda, and its presence in Anas- 

 fides is, therefore, a point of great interest. Claus has suggested, in connection with 

 his discovery of paired otocysts in the head of certain Amphipoda (Oxycephalus), which 

 he regards as probably homologous with the auditory organs of the Decapoda, that the 

 possession of such organs in the region of the head was a character of the primitive 

 Malacostraca* The discovery of the auditory organs of Anaspides certainly lends 

 considerable support to this view. In the male the inner fiagellum of the antennule 

 is modified in a very remarkable manner. The proximal joints of the fiagellum are 

 swollen and distorted, and armed with stout curved serrated spines. While we are as 

 yet completely ignorant of the habits of Anaspides, we may hazard the conjecture that 

 this modification of the antennules in the male is suggestive of a prehensile function 

 rather than the sensory one which Mr Thomson attributes to them. A modification 

 of the antennules for such a purpose, common enough among the Entomostraca, would 

 be almost if not quite unique among Malacostraca. 



Antenna. — The peduncle of the antenna presents only two joints below the origin 

 of the scale or exopodite, agreeing in this respect with the antenna of Euphausiidm, 

 and differing from that of the Mysidse, where three joints are present. The peduncle 

 of the fiagellum, or endopodite, is also remarkable in possessing only two joints (for 

 we do not find the short third joint figured by Mr Thomson) in place of the three 

 joints usual among the Malacostraca. 



* " . . . dass schon zu einer Zeit, in welcher die Edriophthalmen- und Podophthalmenzweige noch uicht geson- 

 dert waren, vor dem Gehirn ein blaschenfbrmiges Sinnesorgan gelegen war, auf welches wir das Gehororgan von 

 Decapoden und Oxycephaliden zuriickzufuhren hatten." — Claus, Crustaceen-System, p. 27. 



