THE SYNC ARID A 167 



distal one swollen and pyriform. While resembling in its position 

 the otocyst of Decapods, this organ differs strikingly from it in the 

 nature of the setae. 



Reproductive System. The ovaries form an elongated lobed mass 

 on each side, extending through the posterior part of the thorax 

 and into the abdomen. The oviducts open on the inner face of the 

 coxopodites of the sixth pair of thoracic limbs. Between the bases 

 of the last pair of legs on the sternal surface of the thorax is a 

 rounded prominence directed forwards. At its tip a slit -like 

 aperture gives entrance to a blind sac, with thick and apparently 

 muscular walls. At the base of the sac on each side is a racemose 

 gland, apparently opening by a short duct into its cavity. It seems 

 probable that this structure (originally described as the opening of 

 the oviducts) is a receptaculum seminis. A similar organ is present 

 in Koonunga. 



The testes are a pair of very long slender tubes, convoluted 

 anteriorly, lying above the alimentary canal. The vasa deferentia 

 terminate in a pair of oblique slit-like apertures on the sternal 

 surface of the last thoracic somite. 



The development, unfortunately, is still entirely unknown. 



KEMARKS ON HABITS, ETC. 



Anaspides occurs in rocky pools at an elevation of about 4000 

 feet in the mountains of Tasmania. It reaches a length of about 

 38 mm. Koonunga is found in freshwater pools near Melbourne, 

 and does not exceed 9 mm. in length. 



PALAEONTOLOGY. 



A group of fossil Crustacea found in Carboniferous and Permian 

 rocks in Europe and America, for which the name Syncarida was 

 proposed by Packard, appear to be closely allied to the living 

 Anaspides and Koonunga. The structure is best known in the case 

 of Uronedes (Gampsonyx) (Fig. 97), described by Jordan and von 

 Meyer from the Lower Permian of Saarbriicken. The exact 

 number of free somites is doubtful, but there appear to be eight 

 in the thoracic region, and there are indications that the sixth 

 abdominal somite was divided in a manner recalling the condition 

 found in certain Mysidacea. The eyes are pedunculated. The 

 antennules are biramous, and the antennae have a rounded scale- 

 like exopodite. One of the anterior pairs of thoracic limbs is 

 enlarged and armed with stout spines. The presence of exopodites 

 on the thoracic limbs is probable, although denied by Fritsch, but 

 the structure of the appendages is very obscure. The uropods are 

 lamellar, forming a tail-fan with the telson ; the exopodites are 



