THE ZOOLOGICAL STATION AT NAPLES. 589 



being in uninterrupted series with the ordinary gills ; that is to say, it 

 lies far back, being just in front of the first permanent gill cleft, and it 

 shows the characteristic tufted structure of the lophobranch gill. I was 

 unable at the time to complete my observations on its development, but 

 they were advanced enough to convince me that the conclusion arrived at 

 for other osseous fishes by Joh. Miiller and Anton Dohrn held good also 

 for the lophobranchs — namely, that the pseudobranch originates in front 

 of the hyomandibular cleft and groove, and that therefore it is homo- 

 logous so far with the spiracular pseudobranch found in many of the 

 cartilaginous fishes. 



B. Intestinal Cdnal. 



The intestinal canal of osseous fishes is well known for its extreme 

 variability in regard to length windings and mesenteric relations. I hoped 

 by studying these points in the comparatively large number of species 

 placed at my disposal to be able to define the characteristic tendencies in 

 the way of morphology which might be expected to be shown by a series 

 of examples ranging from the simpler to the more complex forms of 

 intestinal tube. 



As a result, I have come to these conclusions for all the fishes I 

 examined : 



1. That in any given case the anatomy of the intestinal tube can be 

 regarded either as corresponding directly to, or as being easily derivable 

 from, some one out of a small number of typical forms. 



2. That the typical forms themselves constitute a natural series, of 

 which the more complex members can readily be derived from the 

 simpler. 



Not the least interesting part of my observations had to do with the 

 changes in the morphological scheme indicated above that are produced in 

 the case of certain groups which vary in general form more or less con- 

 siderably from the ordinary piscine type, e.g. in the pleuronectids, which 

 are flattened laterally, or in Lo})hius Fiscatorius, where the flattening is 

 dorsoventral, <tc. Here also must be included those fishes which have the 

 vent carried forward to the front of the abdomen. In all these cases the 

 modified course of the intestinal tube can still be referred to one or other 

 of the typical forms indicated above, by taking in each instance the 

 special factors at work into consideration. 



In addition to investigation, one of the objects of my visit to Naples 

 was to get some knowledgef^f the working of a marine zoological station. 

 For furthering this, as well as for every assistance in work, I have to 

 acknowledge the kindness and courtesy of the station stafi". I consider it 

 a very great privilege to have occupied a table at the Naples Zoological 

 Station, and I hereby tender my sincere thanks to the Committee of the 

 British Association for having afforded me that privilege. 



II. — (1) The Relations hetu-eeii Marine Animal and Vcc/etable Life in 

 Aquaria ; (2) The Relations between the Hybrid and Parent 

 Forms of jEchinoid Larvce. By H. M. Vernon. 



In the report which I furnished last year, I described the work on 

 which I had been engaged during my occupancy of the British Association 

 table at Naples between the months of April and June. I continued to 

 work at the Zoological Station till the middle of the following January, 

 but I only held the British Association table from October onwards, I 



