. Fig. 54. Tetrastemma weddelli, A, outline sketch of the preserved specimen, x 3 approx.; B, graphic reconstruction of the anterior end. Fig. 55. Tetrastemma weddelli, Transverse section across the body, bm, basement membrane; cm, circular muscles; ep, epithelium; hn, longi- tudinal muscles;/), proboscis. There is a single forward diverticulum of the gut which is lateral to the stomach and does not reach the brain. The excretory tubules open dorso-laterally above the lateral nerves. There are two pairs of eyes. In this specimen there is a double eye on one side. The brain is large
. Fig. 54. Tetrastemma weddelli, A, outline sketch of the preserved specimen, x 3 approx.; B, graphic reconstruction of the anterior end. Fig. 55. Tetrastemma weddelli, Transverse section across the body, bm, basement membrane; cm, circular muscles; ep, epithelium; hn, longi- tudinal muscles;/), proboscis. There is a single forward diverticulum of the gut which is lateral to the stomach and does not reach the brain. The excretory tubules open dorso-laterally above the lateral nerves. There are two pairs of eyes. In this specimen there is a double eye on one side. The brain is large and the dorsal ganglia are far larger than the ventral. The ganglia of each side are close together, especially the ventral ganglia at the anterior end (Fig. 54B), so that the ventral commissure is very short. There is a dorsal strand in the lateral nerves. The cerebral organs are large and lie along the dorsal ganglia. They open laterally from their posterior ends, though whether this is connected with the pushing forward of the alimentary canal or the normal position in life I am unable to say. The specimen was a male with ripe sperm.
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Keywords: ., bookcentury1900, booksubjectocean, booksubjectscientificexpediti
