xxii THE VOYAGE OF H.M.S. CHALLENGER. 



Family VII. N E P h T h Y i D .-E. 



Nepthyidx, Verrill, Proc. Essex Inst., vol. vi., 1869, p. 46. 



Siplionogorgiacex, Kolliker, Festschr. phys.-med. Ges. Wiirzburg, 1874, p. 22. 



Spoggodinx, Dana, U.S. Explor. Exped., Synopsis of Report of Zoophytes, p. 126. 



Spoggodidx, Nephthyadee, and LemnaUadse (pars), Gray, Ann. and Mag. Nat. Hist., ser. 4, voL iii. 



pp. 128-130. 

 Alcyoniem armi's, Milne-Edwards, Hist. Nat. des Coralliaires, t. i. p. 127 (pars). 

 Alegoninx mpUuliferse, and Siphonogorgiacex, Klunzinger, Korall. des rothen Meeres, pt. i., 



1877, pp. 30, 48. 



In this family the polyps form upright branched colonies, which consist of a more or 

 less elevated sterile trunk, and of branches ramifying in the most varied fashion and bear- 

 ing terminal polyps. The latter do not exhibit separate calyx and tentacle bearing regions, 

 so that there can be no complete invagination of the upper tentacle-bearing polyp portion 

 into the lower gastral region. The tentacles when at rest are simply folded over the oral 

 disc. The polyp bodies are continued into long gastral cavities, which do not, for the 

 most part, directly communicate with one another, but are separated by thin walls. 

 Each gastral cavity narrows below, and terminates in a cul de sac. A. few, however, 

 are occasionally continued directly into the canals of the stem. The main axis and the 

 larger branches are penetrated by wide canals, which are only separated from one another 

 by thin partitions, sometimes with, sometimes without, spicules. A thicker external 

 sheath, furnished with spicules, surrounds the stems externally, and the large canals are 

 connected with the elongated polyps by tubes which take their origin from the bottom of 

 the polyps. In the walls which separate the polyps there is a system of small capillary 

 sap-canals. From these the young buds arise between the older polyps ; these have longer 

 or shorter digestive cavities according to their age. In the branches four wide 

 canals may be usually distinguished, the walls of which come into contact in the 

 axis of the branch. Fresh polyps, the small tubes of which are visible on cross 

 sections, arise externally from these four principal canals in the interspaces between 

 the pairs. Their partition walls do not, however, extend to the axis. Towards the 

 end of the branch or of the twigs the new buds with their smaller digestive cavities 

 become more abundant. The Nepthyidse appear to have had their origin from 

 among the lower Alcyonids, such as Bellonella, which exhibit analogous relations iu 

 their polyps. 



The family may be divided into two subfamilies : — (a) those in which the walls 

 between the stem-canals include very few or no spicules — the Spongodinse ; and (6) 

 those in which spicules are abundantly present in the walls of the canals — the 

 Siphonogorginse. 



