Hex ACTINIA From nkw south wales, 53 



which is opposite to the longitudinal retractor muscle. It has a depth equal 

 to that of the third cycle o£ mesenteries (PI. 6. fig. 17, p.m.). 



The incomplete mesenteries (PI. 6. fig. 17, me.\ me.^) o£ the second and 

 third cycles are very rudimentary and closely re3eml)le the corresponding 

 mesenteries in Pliellia hrowni. Their feathery appearance in both cases is 

 due to muscle processes of the mesogloea on each side. They are devoid of 

 gonads and muscle-pads. Owing to imperfect preservation I am unable to 

 decide whether a slight mesenterial filament is present on the mesenteries 

 of the second cycle or not, but the mesenteries themselves are quite rudi- 

 mentary and scarcely longer than those of the third cycle. The perfect and 

 imperfect mesenteries of Phellia capitata, unlike those of Phellia hrowni, do 

 not approximate in width towards the pedal disc or become connected with 

 one another. The complete mesenteries in the proximal end of the body 

 meet in the centre of the pedal disc, to which their basal extremities are 

 attached. The incomplete mesenteries are also attached io the pedal disc, 

 but they are narrower and end at varying distances from its centre. The 

 pedal disc, therefore, has a great number of radial lines at its circumference, 

 twelve of which, representing the attachment to the perfect mesenteries, 

 meet in the centre. 



The Acontia (Pi. 6. fig. 17, a.). — The acontia are numerous, thick, and 

 long, but not so dead white as in the former species, and therefore not so 

 prominent at first sight. Transverse sections (PI. 6. fig. 17, a.) show a round 

 figure with a groove on one side. The opposite or convex side is strongly 

 armed with nematocysts, and there is an axis of connective tissue. In form, 

 therefore, the acontia of both Phellia hrowni and capitata closely resemble 

 the acontia described by Hertwig (5) in Cercus spinosus and Calhcetis 

 parasitica, and are unlike those figured by Carlgren for Sagartia viduata, 

 Sagartia undata, Metridium dianthus, and Chondractinia (14) . Unfortunately 

 the muscle-fibres, which Hertwig says " lie on the convex side of the meso- 

 gloea, where the nematocysts lie,'^ and which Carlgren finds in every acontium 

 examined by him "auf der den Nesselzellen entgegengesetzten Seite," are 

 here not well enough preserved to distinguish. 



Gonads (Pis. 5, 6. figs. 14, 16, ^s.).— The specimen was a male and the 

 gonads, carried by the perfect mesenteries only, were extremely well developed 

 and formed large bunches, partly extruded with the oesophagus ; they also 

 almost filled the coelenteron distally, but diminished in size proximally. In 

 the specimen examined it appeared that the perfect mesenteries ceased to bear 

 gonads at different levels, but the state of preservation is not good enough 

 to determine the point. The spermatozoa present are not fully ripe. 



These two Australian species are characterized by the unusual strength of 

 the sphincter and its peculiar contraction into two parts, which does not occur 

 in other known species of the genus. The size and prominence of the 



