436 COLLECTIONS FROM MELANESIA. 



15 millim. in greatest and least thicknesses respectively, spreading 

 over and uniting three detached stones, from which arise two chief 

 and a few incipient lobes, the largest respectively 12 and 25 millim. 

 in height. The species differs from the Torres-Straits and Malacca 

 species (/. purpurea) in the presence of the cylindrical dermal 

 spicule, in the stouter stem, and the much more finely roughened 

 surface; it is more nearly allied to D. (Haliehondria) birotulifera, 

 Higgin (from tho West Indies), which it resembles in stoutness 

 of habit ; but the cylindrical and acuate spicules are both twice the 

 diameter of the corresponding spicules of that form. 



69. Esperia parishi. 



Raphiodesma parish ii, Bowerbank, P. Z. S. 1875, p. 283. 

 Amphilectus parishii, Vosmaer, JVotes Roy. Mus. Netherl. ii. p. 119. 



An indubitable Esperia. Dr. Bowerbank's description of the 

 spi dilation of this species is defective and misleading ; he omits to 

 notice the sheaves of "trichites" which I find in his preparations ; 

 they are, as usual, local in their occurrence, and, from their de- 

 licate proportions, not easy to find ; the slender bihamates described 

 may be traced by intermediate stages up to the large bihamates, 

 which are perhaps the most striking feature of the spiculation ; 

 they are thus merely the young of these latter forms : the alleged 

 spined acuates and tricurvates obviously belong to a Myceilla over 

 which the Esperia has grown, as they occur in abundance together, 

 but not all over the " basal membrane." (Some navicular equi- 

 anchorates which occur seem to be also foreign, being found only 

 detached and in small numbers, and but local in their distribution.) 

 I am inclined to consider the small " palmato-inequianchorates " as 

 young forms of the normal large one. 



The following are the proportions of the different spicules proper 

 to the sponge ; they agree fairly in both the Malacca and Australian 

 specimens : — 



1. Smooth, subspinulate acuate, with slight elongate head; basal 

 end slenderer than middle of shaft : *33 by - 013 millim. 



2. Large inequianch orate ; large end comparatively short, its 

 tubercle long and narrow : "057 millim. long. 



3. Navicular equianchorate : *0 13 millim. long. 



4. Bihamate, smooth, contort : -095 by "008 millim. 



5. Trichite spicules in bunches of two to four or five : -032 to -16 

 by -0018 millim. 



Some thin fragments agreeing well in all respects with the typical 

 pecimen occur in the present collection. 



Hab. Port Darwin, between tide-marks. 



Distribution. Straits of Malacca (Bowerbank). 



This species appears to be absent from Torres Straits, judging 

 from the results of the numerous dredgings taken there : its presence 

 at Port Darwin is therefore probably to be accounted for by direct 

 transit across the western end of the Arafura Sea by way of Timor 

 and the neighbouring islands. 



