STAUROCALYPTÜS MICROCllETUS. 203 



The wall is tolenibly firiii on account of the closely interwoven 

 state of the parenchymal npicules as well as of the small size of 

 the canals. These, both incurreiit and excurient, are never so 

 large as to measure 1 nnn. across. Their ai)ertures lie close 

 together and are indistinctly visible through the tissues (ectosomal 

 or endosomal as the case may be) immediately above them. 



The gastral surface, like the dermal, appears smooth and 

 uniformly compact, ^ome parenchymal needles are seen to project 

 into the gastral cavity but not in considerable numbers. 



I may say that the essential microscopic characters of the 

 sponge are quite unlike those of any other /Skcurocalypius known 

 to me, so that they alone should in my opinion suffice to prevent 

 the species being confounded with any other in the genus. 



Spiculation. 



Some jiarenchymal diactliis, evidently the principalia, are 

 comparatively very lai-ge. They may be as long as 24 mm. with 

 a thickness of 143 /^- in the middle. Such large diactins are 

 invariably without a central swelling; they gradually taper towards 

 both ends wdiich are nearly smooth or only slightly rough. The 

 smaller parenchymalia and the comitalia are of the usual charac- 

 ters. 



The hypodermal pcnlactuis (seen in IM. VIII., fig. 24) are 

 isolated, not in groups. In relation to this fact the four paratan- 

 gentials always are regularly cruciately, and not paratropally, 

 disposed. They are nearly straight or only «lightly bent, meas- 

 uring up to 11mm. in length and 32// in breadth at base. The 



