34 CLASS I. TROPIOPODA. ORDER I. BIMUSCULOSA. 



shell, placed it with the Serpulacea, a family of testaceous Annelides. 

 Lamarck, however, observed that a small bivalve shell was evidently 

 imbedded or grown in with the substance of the tube ; and although the 

 anatomy of the animal and its true mode of habitation still remain in 

 comparative obscurity, the analogy of its structure to other and better 

 known tubicolar Tropiopoda sufficiently indicate the propriety of its 

 arrangement in this family. 



The shell of Aspergillum may be described as being oval, equivalve, and 

 nearly equilateral ; it always remains open, is supposed to cover a por- 

 tion of the back of the animal, and in this position becomes imbedded at 

 the lower side of along clavate testaceous tube, so that the umbones and 

 complete form of it may be distinctly traced on the outer surface ; the 

 tube is then immediately closed over by a convex disc, perforated with 

 numerous tubular holes, like the rose of a common watering-pot; there 

 is also a small fissure in the centre, and the margin is surrounded by a 

 circular frill or row of tubes, supposed during the life of the animal to 

 be filled with fleshy filaments from the mantle. The upper end of the 

 tube, which is rarely obtained perfect, is more or less attenuated, and, 

 terminating in smooth undulations, is reflected at the margin ; some- 

 times, however, it is straight, and somewhat inclined to be compressed. 

 This reflected extremity is left entire at certain periods of growth, and 

 the tube is recommenced according to the necessities of the animal ; 

 some specimens have been found with four or five of these entire ter- 

 minal reflections ; that from which our figure is drawn exhibits four. 



Examples. 



PI. XVII. Fig. 1,2. 



Aspergillum vaginiferum, Lamarck, Anim. sans vert., vol. vi. p. 11. 

 Sowerby, Genera of Shells, No. 27. 



PL XVII. Fig. 3, 4 and 5. 



Aspergillum sparsum, Sowerby, Genera of Shells, No. 27. 

 Aspergillum Javanum, Lamarck ? 



