870 Prof. AUman on the Construction and 



6. MoNOCAULOS*, Allman, nov. gen. 

 Trophosome. — Polypite solitary, borne on the summit of a 

 simple rooted hydrocaulus; both hydrocaulus and hydrorhiza 

 invested by a very delicate periderm; polypites flask-shaped, 

 with two sets of filiform tentacles, — a proximal set longer and 

 thicker, and arranged in a single verticil near the base of the 

 polypite, and a distal set shorter and thinner, and scattered over 

 a zone close to the summit of the polypite. 



Gonosome. — Gonophores adelocodonic, on simple or branched 

 peduncles, which spring from the body of the polypite at the 

 distal side of the longer tentacles. 

 Monocaulos glacialis, Sars (sp.), = Corymorpha glacialis, Sars. 

 Monocaulos pendula, Agass. (sp.),= Cort/morpha pendula,Aga,ss. 



7. Nemopsis, Agassiz. 



Trophosome. — Polypite free, conical, with two verticils of fili- 

 form tentacula — a proximal near the base, and a distal near the 

 apex; periderm absent. 



Gonosome. — Gonophores phanerocodonic, on short simple 

 peduncles which spring from the body of the polypite between 

 the two verticils of tentacula. Umbrella deep bell-shaped ; ma- 

 nubrium of moderate size, and furnished with four dichotomously 

 branched oral tentacles ; radiating canals four, each terminating 

 in a marginal bulb, while from every marginal bulb a tuft of 

 tentacles is given oif, two of the tentacles in each tuft being 

 clavate and but slightly contractile, the rest filiform and very 

 contractile, every tentacle carrying a distinct ocellus at its base. 

 The generative elements are developed in four lobse, which 

 spring from the base of the manubrium and thence extend for 

 some distance along the course of the radiating canals. 



Nemopsis Gibbesii, M'Crady. 



8. AcAULis, Stimpson. 



Trophosome. — The entire trophosome consists of a solitaiy, 

 free, subfusiform polypite, which, at a later period, becomes at- 

 tached by its proximal extremity ; tentacles of two kinds, — one 

 filiform, forming a single verticil near the proximal extremity, 

 and subsequently disappearing — the other^capitate, and scat- 

 tered on the body of the polypite towards its distal extremity ; 

 periderm absent. 



Gonosome. — Gonophores phanerocodonic, springing from the 

 body of the polypite between the filiform and capitate tentacula. 

 Form of the Medusa unknown. 



Acaulis primarius, Stimpson. 



* From fwvos, single, and KavKos, a stalk. 



