PORIFERA. II. 



197 



varidens . . . 



oxeata 



abyssi Cart. 

 dubia 



intermedia . 

 rotulancora 



polydentata 



affinis 



spinosa . . . . 



Megasclera 

 Skeletal spicules 



Dermal spicules 



Styli 



0-51-0-608""" 



oxea 



0-56—0-68""" 

 oxea and styli 

 0-6—0-67""" 0-408— o-49 mm 

 styli 



0-46—0-536'""' 



most frequently slight spines 

 at the head-end. 



0-357— o-48 ram 

 0-40 — 0-55™"' 



042— 0-57"" 

 o'47— 0-57- 



0-40— 0'52 n " 



spined. 



tylota 



0-298— 0-38"" 



0-32— 042"" 1 

 0-298—0-357'" 



°-34-°"3 8ran: 



0-26— o-34 m,r 

 0-30 — o - 4i mn 



o-25-o-34 m " 



o'35-o-44 m " 

 0-24 — o - 34 mn 



Microselera 



ancorae 



5— S free teeth. 



0-054—0-0657""" 



g — 13 free teeth. 



0-048—0-065""" 



more than 6 teeth. 



0-055—0-06""" 



7 — 9 free teeth 



0-038 — 0-050'" m 



9 — 11 free teeth 

 0-040 — 0-050""" 



12 — 17 teeth 



0-030 — 0-040'" m 



birotulae, large 



12—20 teeth 

 0-020 — 0-028 mm 



9 — 13 teeth 

 0-037 — 0-051'""' 



8 — 12 teeth 

 0-031 — 0-045""" 



birotulae, small 



9—14 teeth 



0-015 — o-oi8"' m 



13 — ca. 20 teeth 

 0-015— 0-020 mm 



ea. 12 — 14 teeth 

 0-015 — o-oi8 mm 



11 — 14 teeth 

 0-OI8—0-02 I mm 



14—15 teeth 

 0-018 — 0-02I""" 



9—12 teeth 

 0-018 — 0-032""" 



9—14 teeth 



0-0128— o-oi8 mm 

 11 — 15 teeth 



0-018— 0-025 mm 

 9 — 13 teeth 



0-018 — 0-024""" 



The ancorae occurring in species of this genus form quite evidently a transition to birotulae, 

 what is seen especially distinctly in the species rotulancora. On the other hand, these ancorae are 

 evidently allied to such forms as those found in Chondrocladia and C/ador/iiza, and these forms lead 

 again, I suppose, to the other existing forms of ancorae. Lindgreeu (Zoologisch. Jahrbrich. XI, 1898, 

 355) says that the birotulae occuring in lotrochota must either be supposed to be only analogous to 

 the ancorae of the other Desmacidonidae, or else to represent a more original form. I think the latter 

 supposition the more correct one. Birotulae have also in their structure so great resemblance to the 

 amphidisci of the Hexactinellida, that it is difficult to divest one's mind of the idea of a relation 

 between these bodies. 



The /otroc/wta-species may show some difference with regard to the spicules. As will have 

 been seen, the species described here are separated into two groups, those having ancorae and biro- 

 tulae, and those having only birotulae; the separation is of no greater systematic importance, on 

 account of the transition between ancorae and birotulae. Also with regard to the megascleres some 

 difference may be found. The skeletal spicules are typically smooth styli; they may be spined (spi- 

 nosa), sometimes they may be rounded at the pointed end (birotulata) , further they may be oxea 

 (oxeata), and finally they may be a mixture of styli and oxea (abyssi, accrata). The dermal spicules 

 are typically tylota, but may be monactinal (purpurea, birotulata, magna, coccinea); this fact, however, 

 is of no real importance, as the dermal spicules are upon the whole only secondarily diactinal. 





