EMBRYONIC DEVELOPMENT 365 



second specimen, collected on March 14, contains numerous large embryos, spherical or 

 oval in shape, of a rich yellowish brown in colour which makes them very conspicuous, 

 and measuring up to i mm. in longest diameter. There is no sign of spicules or of a 

 marked differentiation into an inner cell mass and an outer layer of smaller cells. 



Isodictya antarctica (Kirkpatrick). A specimen, collected on June 21, contains 

 numerous large embryos similar to those of /. setifer, but more golden yellow in colour 

 and measuring up to o-8 mm. in diameter. 



Guitarra fijnbriata, Carter. A specimen, collected on July 17, contains a few aspicu- 

 lous embryos, situated just beneath the surface, and measuring o-i mm. in diameter. 



Mycale magellanica (Ridley). A specimen, collected on September 20, contains a few 

 embryos in an early stage of development, 0-12 mm. in diameter. 



Amphilectus fiicoriim (Johnston). A specimen, collected on March 24, contains 

 numerous aspiculous embryos, spherical or oval, measuring 0-28 mm. in diameter, and 

 a second specimen, collected on May i, has oval embryos measuring o-i6 mm. in 

 longest diameter. 



Asbestopluma calyx, Hentschel. A specimen, collected on January 20, contains nu- 

 merous embryos in an advanced stage of development. The spicules contained are 

 clavate tylostyli (or styli), o-i by 0-007 mrn., and anisochelae, o-oii mm. chord. In the 

 earliest stages seen tylostyli only are present, forming a compact bundle at the centre 

 of the embryo. In others anisochelae have made an appearance and are scattered ir- 

 regularly around this bundle, and in the most advanced embryos the bundle of tylostyli 

 is surrounded at its upper (?) end by a dense corona of anisochelae (Fig. 54 k). 



lophorr radiatiis Topsent. Specimens, collected from January 9 to June 21, all contain 

 embryos in an early stage of development. Those described by Kirkpatrick (1908), 

 which are at a later stage of development, were obtained in February. 



Anchinoe latninculioides (Ridley and Dendy). A single specimen, collected on 

 June 17, contains large oval, aspiculous embryos, measuring 0-4 mm. in longest diameter. 



Anchinoe leptochela (Hentschel). The single specimen, collected in April, contains 

 numerous embryos. Some are aspiculous, slightly flattened at one pole and measuring 

 0-32 mm. diameter. Others, of approximately the same size but regularly spherical, 

 contain numerous chelae of the same shape as those in the adult and, in some instances, 

 a few acanthostyli. The chelae measuring 0-021 mm., about two-thirds the size of those 

 of the adult, and the acanthostyli 0-092 mm. long. 



Kirkpatrickia variolosa (Kirkpatrick). One specimen, collected on December 19, is 

 filled with spherical embryos, 0-036 mm. diameter, most of which are in a comparatively 

 early stage of development. The most advanced stage, and one rarely met with in this 

 specimen, shows a compact central mass of cells with a single epiblastic layer, and 

 internally a few incipient acanthostyli 0-035-0-12 mm. long. 



Plocamia gaussiana, Hentschel (Fig. 546-?'). Several specimens contain embryos: 

 those taken in December contain only a few aspiculous embryos (i.e. early stages); 

 those taken in January contain numerous embryos in varying stages of development, but 

 all, or nearly all, possessing spicules. From these, the course of development may be 



