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Part III. — Eighteenth Annual Report 



maxillipedes, 22mm. ; length of head and thorax (anterior to the angle 

 from whence the second maxillipedes spring), 9mm. ; length of posterior 

 portion of thorax, 15mm. ; length of ovisacs, 20mm. ; length of the 

 ventral thoracic appendages, 10mm. ; total length from the apices of 

 second maxillipedes to the end of ovisacs, 55mm. (nearly 2J inches). 



The male of this large copepod scarcely reaches beyond two millimetres 

 in length. 



The antennules in the female are apparently three-jointed, and are 

 moderately stout. The antennae are short, stout, and feebly clawed (fig. 

 8). The mandibles, which are of moderate length and somewhat slender, 

 are serrated at the distal end of the inner margin (fig. 9). The anterior 

 foot-jaws (maxillipedes) are stout and feebly clawed. 



In the male the thorax and abdomen (fig. 7) are more or less seg- 

 mented) ; and the maxillipedes are short and stout, and, being armed with 

 strong terminal claws, form powerful grasping organs. 



Habitat. — In the nasal fossae (or spiracles) of the grey skate, Raia 

 batis. All the specimens we have obtained have been found in the nasal 

 fossad of the grey skate. Charopinus dalmanni appears to be moderately 

 common on the large skate brought to the Fish Market at Aberdeen ; 

 sometimes two and three specimens have been found in the same spiracle 

 of the skate examined in the market. I have also taken this species 

 from a grey skate captured at the mouth of the Forth estuary. 



Charopinus dubius, sp. n. 



I record provisionally under- this name a Charopinus which has been 

 obtained adhering to the gills and gill-arches of the cuckoo ray, Raia 

 circularise Couch. The fishes from which these conepods were obtained 

 were captured in the Firth of Clyde during December 1899. No 

 specimens of this copepod have so far been observed in the spiracles of the 

 cuckoo ray. 



This Charopinus resembles more or less closely the Charopinus of the 

 grey skate, and may only be a form of that species. The following points, 

 however, deserve notice : — 



Charopinus dubius is distinctly smaller than Charopinus dalmanni. 

 The second maxillipedes are more slender in proportion to their length, 

 and they are joined to each other at the apex by small horn-coloured plugs, 

 which unite to form a thin circular horny disk, hollow in the middle and 

 with the margins slightly renexed. This disk is usually buried in the hard 

 substance of the gill-arches, and is difficult to dissect out while retaining 

 its union with the maxillipedes. The ovisacs are also rather more 

 elongate and slender. 



The most obvious difference between Charopinus dalmanni and the 

 present form, other than that of size, is the character of the apices of the 

 second maxillipedes ; the difference here is very distinct and must of itself 

 be held as alone of specific value if the differences recognised by Kroyer 

 are to be considered valid. According to that distinguished observer, the 

 more important specific characters by which Charopinus dalmanni 

 (Retz.) and Charopinus ramosus, Kr., are distinguished, are taken chiefly 

 from the form assumed by the apices of the second maxillipedes. Kroyer's 

 definitions of these species are as follow : — 



" Charopinus dalmannii. 

 *Laminae cartilagineae, quibus affigitur femina, semilunares." 

 *Naturh. Tidsskr., R. 3, Bd. 2 (1863-64), p. 362. 



