and Acapulco S2)onges. 285 



Group (). Haliciiondrina. 



TlaJichondrla isodicfi/ah'sj n. sp. 



Massive, sessile, lohate. Consistence fragile. Colour lig-ht 

 fawn. Surface uniformly reticulate in relief, except where 

 interrupted by a vent. Vents scattered over the surface 

 generally. Structure crumb-of-bread- like, reticulate, delicate, 

 fragile, traversed by the branches of the excretory canal-system. 

 Spicules of four forms, viz. : — 1, skeletal, acuate, smooth, 

 curved towards the blunt end, which is rather smaller than the 

 rest of the shaft ; gradually sharp-pointed, about 40 by 1-^- 

 6000th inch in its greatest dimensions (PI. XI. tig. 2, a) ; 2, 

 subskcletal, a tibiclla with slightly fusiform shaft and inflated 

 ends, about 50 by l^-6000th inch in its greatest dimensions 

 (fig. 2, b) ; 3, flesh-spicule, equianchorate, shaft simple, curved, 

 arms slightly everted, about one third of the length of the 

 shaft, 6-GOOOths inch long (fig. 2, cc) ; 4, flesh-spicule, 

 simple, C-shaped, sigmoid, bihamate, 4-GOOOths inch long 

 (fig. 2, (/). Nos. 1 and 2, intermixed generally, are chieHy 

 confined to the spiculo-skeletal structure, which is arranged 

 isodictyally ; nos. 3 and 4 are scattered more or less abun- 

 dantly throughout the sarcode. Size of largest fragment, of 

 which there are several (allof which appear to have come from 

 the same mass originally, as they are all intermingled with 

 the same species of coralline, viz. Flahellaria ojjuntia), 4x3 

 X 2 inches. 



Ilab. Marine. Growing about and enclosing Flahellaria 

 ojjuntia in the West Indies, or densely charged with miliary 

 gravel at Acapulco. 



Loc. Puerto Cabello and harbour of Acapulco. 



Ohs. The external appearance of this sponge, where it is 

 most free from the objects among which it has been growing, 

 is very like that of Ilalichondria incrustans ; but the isodictyal 

 arrangement of the spiculo-skeleton, the spineless acuate, and 

 the shaft of the anchorate being simple instead of intlated 

 above and below the middle (as in U. incrustans) , are suffi- 

 cient differences to establish a distinction, and to call for a 

 diflerent designation ; hence the term " isodictyalis.''^ 



The specimens, which are charged with the miliary gravel 

 among which the sponge has thus grown, were dredged in tiie 

 harbour of Acapulco, in 4-9 fi\thoms, by Capt. W. 11. Cawne 

 Warren. 



Jlalicliondria imshdosa^ n. sp. (PL XI. fig. 1, a-g.) 

 Erect, branched irregularly, branches nodose or knotted 



