Archive image from page 71 of The Danish Ingolf-Expedition (1918). The Danish Ingolf-Expedition danishingolfexpe0507ingo Year: 1918 64 HYDROIDA II 4 have monosiphonic stem; not until later does it become canaliculate, and finally, in fullv developed colonies, we find purely polysiphonic basal parts of the stem, where secondary tubes cover the canali- culate central tube. Thus the limits between Nemertesia and Antennopsis become effaced, and these genera must in consequence, as I have previously maintained (1912 p. 28), and as Stechow also points out (1913 p. 25) be united into one. Similar
Archive image from page 71 of The Danish Ingolf-Expedition (1918). The Danish Ingolf-Expedition danishingolfexpe0507ingo Year: 1918 64 HYDROIDA II 4 have monosiphonic stem; not until later does it become canaliculate, and finally, in fullv developed colonies, we find purely polysiphonic basal parts of the stem, where secondary tubes cover the canali- culate central tube. Thus the limits between Nemertesia and Antennopsis become effaced, and these genera must in consequence, as I have previously maintained (1912 p. 28), and as Stechow also points out (1913 p. 25) be united into one. Similarly it follows, that Stechow is correct in placing Sibogella under Nemertesia. Bedot, in a work which has just appeared (1917) treats of the genus Nemertesia at length, unfortunately, however, without giving any synopsis of the generic characters. It is nevertheless clear that Bedot inclines to regard the canaliculate ('pluricanaliculee') stem as a family trait. The char- acter is developed, as mentioned above, only in somewhat larger colonies — generally at least 5 cm high — it is moreover often lacking in large distal parts of the colony in the northern species, where the stem fre- quently retains its primary ('unicanaliculee') character. And finally, the primary 'pluricanaliculee' stem tube is secondarily covered, as in Nemertesia ramosa, by tubes 'unicanaliculees' to a greater or lesser extent. This in itself detracts from the value of the character in question. But in addition, it is also found to stand in a certain relation to the dimensions of the stem tube; thick, single stems are 'pluricanaliculees' in spe- cies within the same genus, where the thin ones are constantly 'unicanaliculees' (cf. for instance Tubularia). As a matter of fact, the two types 'fasciculee' (poly- siphonic) and 'pluricanaliculee' (canaliculate) represent Fig. xxx a—c. Nemertesia antennina, juv. 'Ingolf' St. 98. parallel processes of development towards the same a. The entire colonv (nat. siz
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