470 EECOED OF CURRENT RESEARCHES RELATING TO 



middle of each of the hexagonal facets.* Genera: Challengeria, Tusca- 

 rora, Gazelletta, Porcupinia, Entocanula, Lithogromia. 



Family 5. CastanellidfB. — The siliceous skeleton consists of a 

 simple roimd fenestrated shell, which has in one part of its upper 

 surface a wide opening, often surrounded by peciiliar processes. The 

 fenestrated shell is usually ornamented with solid or hollow spines. 

 Genera : Castanella, Castanidium, Castanissa, Castanopsis, Casfanura. 



Family 6. Circoporidae. — The siliceous skeleton consists of a sub- 

 sj)herical or polyhedral siliceous shell, from which radiate in different 

 directions hollow tubes (simple or branched, often provided with 

 whorls of cilia). The shell has a large opening, as well as scattered 

 pore-facets. The pores usually form circles round the bases of the 

 spines.f Genera : Circoporus, Circospathis, Circosteplianus, Poroste- 

 phanus, PorospatMs. 



Order III. Phfeosphseria. — The siliceous skeleton consists of 

 numerous hollow tubes which are combined in a peculiar manner into 

 a large, usually round or polyhedral fenestrated body. 



Family 7. Aulosphseridas. — The siliceous shell is a fenestrated ball 

 or a fenestrated polyhedral body whose lattice-work is formed of hollow 

 tubes. Hollow spines usually radiate from the points of connection 

 of the lattice-work.| Genera : Aulosphcera, Aulodictyum, Auloplegma. 



Family 8. Cannosphseridse. — The siliceous skeleton consists of a 

 imiaxial globular or oval simple bounding shell, which is connected 

 by means of hollow radial rods with a composite outer encrusting 

 shell. The outer shell consists of hollow tubes which form a wide- 

 meshed latticed sphere ; hollow simple or branched radial spines 

 spring from the junctions of the lattice.§ Genera : Cannacantha, Can- 

 nosphcera, Coelocantha. 



Order IV. Phjeoconchia. — The siliceous skeleton consists of two 

 separate fenestrated shells, like those of a bivalve mollusc. Simple or 

 branched hollow tubes are often found at the junction of the valves. 



Family 9. Concharidee. — The siliceous skeleton consists of two 

 semicircular or lenticular fenestrated shells turned each to each with 

 the concavities inwards ; the edges of the shells are usually set with 

 rows of teeth, which lock together like the teeth of a bivalve. || Genera : 

 Concharium, Conchopsis, Conchidium, Conchoceras. 



Family 10. Coelodendridse. — The siliceous skeleton consists of 

 two semicircular or lenticular fenestrated shells with the concave 

 sides turned towards each other. Simple or tree-like branched hollow 

 spines spring from the two opi^osite poles of the principal axis, or 

 from the centre of the junction of the hemispheres. 1[ Genera : Coelo- 

 dendrum, Coelothamnus, Coelodrymus, Coelothauma. 



Parasitic Acinetse.** — Mr. W. G. Cocks records the discovery of a 

 branched group of Epistylis, to which were attached several Acinetce. 



* Cf. Murray, I. c, pi. xxiv. fi?s. 1, 2, 4. f Ibid., figs. 5, 6. 



t Haeckel, ' Monogr. d. Radiol.,' 1862, p. 357, taf. x. xi. 

 § Hertwig, ' Organ d. Eadiol.,' 1879, p. 91, pi. ix. 

 II Cf. Murray, I. c, pi. xxiv. fig. 3. 



if Haeckel, ' Monogr. d. Eadiol.,' 1862, p. 360 ; taf. xiii., figs. 1-4 ; taf. xxxii., 

 figs. 1-3. 



** ' Sci.-Gossip,' 1880, p. 79 (3 figs.). 



