30 



Trop. tegens 1 ). Incrusting, tending to become thicker, thus forming cushions or thick trabeculae. 

 Surface glabrous, hence more or less shining or glossy. Structure pretty compact. In 

 addition to small spinispirae, robust ones occur. Typical representatives are: Spir. 

 decumbens (B. M. 27, B. M. 38, B. M. 39) ; Spir. bistellata (G. M. 73) ; 1031, 1455 a-d ; 1945. 

 Here may be included, though not as typical forms : S. transitoria (B. M. 30), S. semilunaris, 

 1402, 1421- 



Trop. tuberosa. Massive, more or less broad-conical. Surface with numerous tubercles or papillae, 

 sometimes with rugae ; subglabrous, hence somewhat glossy. Structure pretty compact. 

 In addition to small spinispirae, very large, robust ones occur, forming a cortical crust. 

 Typical representatives are : Spirastrclla citnctatrix (B. M. 1, B. M. 3, B. M. 10. B. M. 13, 

 B.M. 16), S. panis, S. insignis, S. papil losa, g2a-l, 426c!. 5. eunctatrix described by 

 Schmidt is said to be incrusting, and as such forms a transition to trop. tegens. Schmidt 

 states that the spinispirae are often short and thick, resembling those of his Suberites 

 bistellatus. This is also the case in Spir. amctatrix B. M. 3 ; herein we have another 

 suggestion for the specific identity between trop. tegens and trop. tuberosa. 



Trop. pyramidalis. Typically the shape is pyramidal, at the base often provided with conical 

 or digitate processes. At the top of the pyramid there generally is a small opening which 

 leads in a main central wide canal. Surface subglabrous, somewhat shining. Often distinctly 

 purple or carmin-red. The larger spinispirae are exceedingly variable in shape and size; 

 they may be very scarce, even disappear. Typical representatives are : Suberites wilsoni 

 (B.M. 15, B.M. 22, B.M. 32, B.M. 33), 426 a-c The shape of Alcyonitun purptireum 

 is unknown ; probably not pyramidal but "massive, cushion-like", as Bowerbank states 

 about Hymeniacidon piilvinatus. If this be so there is reason to include specimens like 

 300, 410 etc. within the tropus. We may also include : Spir. arcolata, S. massa and 

 5. bonnet i\ further 1949, 1988, 1950, 1480, 1045- Characteristic is further that the tylostyli 

 often form thick bundies, especially towards the periphery, thus simulating a cortex. 



Trop. digitata. Massive; from a broad base digitate processes tend to grow up; these may be 

 short and thick, giving to the sponge a more massive appearance or elongated, fingershaped. 

 The robust spinispirae we saw still frequently present in trop. pyramidalis are always 

 wanting. The small spinispirae form a superficial crust. Like in typical specimens of trop. 

 pyramidalis their is a large, central canal; generally we find secondary large canals 

 around the central one. Typical representatives are: S. vagabunda (B.M 17, B.M. 19, 

 B. M. 14, B M. 24, B. M. 36, B. M. 41, ^'. rongenera (B. M. 20), 5. punctulata (B. M. 28), 

 948 a-f. More or less modified are 614 a-b, 143, 1117, 1391, 1610, 1631- Very likely 5". solida, 

 S. teutorioides, S. carnosa have to be included here. As stated before it is a mere 

 question of taste whether 1403 and 1075 shall be included in trop. digitata or in trop. 

 pyramidalis. With S. wilsoni B. M. 15 they are closely allied in respect to the spinispirae. 



Trop. tnbitlifera. Typically start from a broad base digitate or cylindrical processes. In these 

 processes a wide central canal is visible, which opens at the top with a wide mouth. 



1) tego, I cover. 



