1G THE VOYAGE OF H.M.S. CHALLENGER. 



parietal spherules, and reaching to the origin of the tentacles, extends therefore over a 

 airly wide belt. Correspondingly to this broad extension, it is nowhere strongly 

 developed, and falls under the category of " diffuse " endodermal muscle, the lamella 

 being most markedly pleated in the centre. Its arrangement is very characteristic, as 

 a transverse section presents the appearance of numerous closely-packed acinose glands, 

 excavated in the mesoglcea. In the more central parts — to continue the comparison — 

 the gland-like crypts are longer and more closely packed than in the upper and 

 lower parts (PL II. fig. 1). 



The strongest development of muscles occurs on the ectodermal side of the disc, 

 where the supporting lamina rises into high plates, covered by strong fibrils and 

 richly arborescent. Here and there I have also noticed the plates fusing together, with 

 a resultant mesodermal inclusion of the muscle fibrils (PI. II. fig. 3). Towards the 

 tentacles the muscles become weaker. 



The tentacles are of a medium length, broad at the base, and drawn out to a fine 

 point, which is probably not provided with an opening at the tip. The siphonoglyphes 

 are hardly marked on the stomatod?eum. To the latter, besides the mesenteries of the 

 first cycle, those of the second and third cycles at least are attached. Their musculature 

 is in no region strongly developed ; in the specimen investigated nearly ripe testicular 

 follicles occurred on them. 



Family 4, Bunodid^e. 



Genus Aulactinia, Verrill. 



Aulactinia, sp. (?) * 



Habitat. — Simon's Bay, Cape of Good Hope, December 1873; 10-20 fathoms. 

 One specimen. 



Dimensions. — Height in a strongly contracted condition, 2 cm. ; breadth of pedal 

 disc, 3 cm. 



In this place I will devote only a few words to a Bunodidan, of which I reserve 

 a detailed description till I shall have reviewed a rich supply of species of this 

 family which has been forwarded to me. The body-wall of the sole specimen lying 

 before me is thickly beset with thin-walled vesicular outgrowths, which are about 

 1 mm. in size, show a tendency towards arrangement into transverse and longitudinal 

 rows, and are so thickly set that the intermediate stouter parts of the body-wall have 

 a reticulate appearance. The three upper rows of these vesicles (about seventy in 

 number) are closely packed with nematocysts, and so take on the character of marginal 

 spherules ; they may be distinguished into a stalk, and a branching head like a cauli- 

 flower. They recall somewhat those external appendages of species of Oulactis, which 



