S2 The Genera of the Plumulariidoe, 



norvegica of Sars, in which the hydroclaclia are in threes, 

 with a sub-spiral arrangement ; the Nemertesia decussata of 

 Kirchenpauer, which has the hydroclaclia in pairs, each pair 

 being in a plane at right angles to that of the pairs next 

 above and below, so as to form four series on the stem ; and 

 the Antennopsis hippuris of Allman, in which they are 

 without definite order. Professor Allman now considers 

 Antennopsis not distinct from Antennularia. 



SciURELLA, Allman. 



Hydrocladia disposed round the stem ; sarcothecse not 

 attached to the hydrotheca. 



Gonangia with horn-like processes^ and a ramified blasto- 

 style. 



The only species known has the hydrocladia arranged as 

 in Antennularia decussata, and difiers from Antennularia 

 only in the gonosome. 



The genera already passed in review belong, so far as is 

 known, to the Gymnocarpa ; the two remaining genera, 

 Hippurella and Callicarpa, constitute the Phylactocarpal 

 section of the Eleutheroplea. Each of these genera is at 

 present represented by a single species only ; both are from 

 the North American coast, and both are very similar in the 

 minute structure of the trophosome.* 



Hippurella, Allman. 



Trophosome as in Plumularia. 



Gonangia protected by phylactocarps, which consist of 

 ^ematocladia arranged verticillately at the tips of the 

 ordinary branches. 



Professor Allman described this genus in the Report on 

 the Gulf Stream Hydroids, but supposed the verticillate 

 branchlets to be hydrocladia. Mr. Fewkes, on further 

 examination, found that they were provided with nemato- 

 phores instead of hyclrothecte, constituting a phylactocarpal 

 gonosome. In the only known species there are six ramuli 

 in each verticil. 



* In the " Catalogue" I have inadvertently stated that these genera have a 

 similar trophosome to that of Aglaophenia. 



